diff --git a/packages/app-next/src/index-public-experimental.tsx b/packages/app-next/src/index-public-experimental.tsx
index 4c01c428df..ce558ed4f0 100644
--- a/packages/app-next/src/index-public-experimental.tsx
+++ b/packages/app-next/src/index-public-experimental.tsx
@@ -15,9 +15,13 @@
  */
 
 import ReactDOM from 'react-dom/client';
-import { createPublicSignInApp } from '@backstage/frontend-defaults/alpha';
+import { createApp } from '@backstage/frontend-defaults';
+import { appModulePublicSignIn } from '@backstage/plugin-app/alpha';
+
 import '@backstage/ui/css/styles.css';
 
-const app = createPublicSignInApp();
+const app = createApp({
+  features: [appModulePublicSignIn],
+});
 
 ReactDOM.createRoot(document.getElementById('root')!).render(app.createRoot());
diff --git a/packages/frontend-defaults/package.json b/packages/frontend-defaults/package.json
index 4bbbf8986d..5a2cfb6eb3 100644
--- a/packages/frontend-defaults/package.json
+++ b/packages/frontend-defaults/package.json
@@ -5,7 +5,9 @@
     "role": "web-library"
   },
   "publishConfig": {
-    "access": "public"
+    "access": "public",
+    "main": "dist/index.esm.js",
+    "types": "dist/index.d.ts"
   },
   "repository": {
     "type": "git",
@@ -14,23 +16,8 @@
   },
   "license": "Apache-2.0",
   "sideEffects": false,
-  "exports": {
-    ".": "./src/index.ts",
-    "./alpha": "./src/alpha/index.ts",
-    "./package.json": "./package.json"
-  },
   "main": "src/index.ts",
   "types": "src/index.ts",
-  "typesVersions": {
-    "*": {
-      "alpha": [
-        "src/alpha/index.ts"
-      ],
-      "package.json": [
-        "package.json"
-      ]
-    }
-  },
   "files": [
     "dist"
   ],
diff --git a/packages/frontend-defaults/report-alpha.api.md b/packages/frontend-defaults/report-alpha.api.md
deleted file mode 100644
index 1bd66e6521..0000000000
--- a/packages/frontend-defaults/report-alpha.api.md
+++ /dev/null
@@ -1,15 +0,0 @@
-## API Report File for "@backstage/frontend-defaults"
-
-> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
-
-```ts
-import { CreateAppOptions } from '@backstage/frontend-defaults';
-import { JSX as JSX_2 } from 'react';
-
-// @alpha
-export function createPublicSignInApp(options?: CreateAppOptions): {
-  createRoot(): JSX_2.Element;
-};
-
-// (No @packageDocumentation comment for this package)
-```
diff --git a/plugins/app/package.json b/plugins/app/package.json
index 199054f141..9cefaa8609 100644
--- a/plugins/app/package.json
+++ b/plugins/app/package.json
@@ -11,9 +11,7 @@
     ]
   },
   "publishConfig": {
-    "access": "public",
-    "main": "dist/index.esm.js",
-    "types": "dist/index.d.ts"
+    "access": "public"
   },
   "repository": {
     "type": "git",
@@ -22,6 +20,21 @@
   },
   "license": "Apache-2.0",
   "sideEffects": false,
+  "exports": {
+    ".": "./src/index.ts",
+    "./alpha": "./src/alpha/index.ts",
+    "./package.json": "./package.json"
+  },
+  "typesVersions": {
+    "*": {
+      "alpha": [
+        "src/alpha/index.ts"
+      ],
+      "package.json": [
+        "package.json"
+      ]
+    }
+  },
   "main": "src/index.ts",
   "types": "src/index.ts",
   "files": [
@@ -47,12 +60,15 @@
     "@material-ui/core": "^4.9.13",
     "@material-ui/icons": "^4.9.1",
     "@material-ui/lab": "^4.0.0-alpha.61",
+    "@react-hookz/web": "^24.0.0",
     "react-use": "^17.2.4"
   },
   "devDependencies": {
     "@backstage/cli": "workspace:^",
     "@backstage/dev-utils": "workspace:^",
+    "@backstage/frontend-defaults": "workspace:^",
     "@backstage/frontend-test-utils": "workspace:^",
+    "@backstage/test-utils": "workspace:^",
     "@testing-library/jest-dom": "^6.0.0",
     "@testing-library/react": "^16.0.0",
     "@testing-library/user-event": "^14.0.0",
diff --git a/plugins/app/report-alpha.api.md b/plugins/app/report-alpha.api.md
new file mode 100644
index 0000000000..9496430e7b
--- /dev/null
+++ b/plugins/app/report-alpha.api.md
@@ -0,0 +1,12 @@
+## API Report File for "@backstage/plugin-app"
+
+> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
+
+```ts
+import { FrontendModule } from '@backstage/frontend-plugin-api';
+
+// @alpha
+export const appModulePublicSignIn: FrontendModule;
+
+// (No @packageDocumentation comment for this package)
+```
diff --git a/packages/frontend-defaults/src/alpha/createPublicSignInApp.test.tsx b/plugins/app/src/alpha/appModulePublicSignIn.test.tsx
similarity index 91%
rename from packages/frontend-defaults/src/alpha/createPublicSignInApp.test.tsx
rename to plugins/app/src/alpha/appModulePublicSignIn.test.tsx
index 58a264e81d..14dba9416b 100644
--- a/packages/frontend-defaults/src/alpha/createPublicSignInApp.test.tsx
+++ b/plugins/app/src/alpha/appModulePublicSignIn.test.tsx
@@ -20,18 +20,20 @@ import {
 } from '@backstage/frontend-plugin-api';
 import { render, screen, waitFor } from '@testing-library/react';
 import { useEffect } from 'react';
-import { createPublicSignInApp } from './createPublicSignInApp';
+import { appModulePublicSignIn } from './appModulePublicSignIn';
 import { mockApis } from '@backstage/test-utils';
+import { createApp } from '@backstage/frontend-defaults';
 
-describe('createPublicSignInApp', () => {
+describe('appModulePublicSignIn', () => {
   beforeEach(() => {
     jest.resetAllMocks();
   });
 
   it('should render a sign-in page', async () => {
-    const app = createPublicSignInApp({
+    const app = createApp({
       configLoader: async () => ({ config: mockApis.config() }),
       features: [
+        appModulePublicSignIn,
         createFrontendModule({
           pluginId: 'app',
           extensions: [
@@ -57,9 +59,10 @@ describe('createPublicSignInApp', () => {
       .spyOn(HTMLFormElement.prototype, 'submit')
       .mockReturnValue();
 
-    const app = createPublicSignInApp({
+    const app = createApp({
       configLoader: async () => ({ config: mockApis.config() }),
       features: [
+        appModulePublicSignIn,
         createFrontendModule({
           pluginId: 'app',
           extensions: [
diff --git a/packages/frontend-defaults/src/alpha/createPublicSignInApp.tsx b/plugins/app/src/alpha/appModulePublicSignIn.tsx
similarity index 59%
rename from packages/frontend-defaults/src/alpha/createPublicSignInApp.tsx
rename to plugins/app/src/alpha/appModulePublicSignIn.tsx
index 90c6e5e178..4a188d1d5f 100644
--- a/packages/frontend-defaults/src/alpha/createPublicSignInApp.tsx
+++ b/plugins/app/src/alpha/appModulePublicSignIn.tsx
@@ -1,5 +1,5 @@
 /*
- * Copyright 2024 The Backstage Authors
+ * Copyright 2025 The Backstage Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,16 +14,14 @@
  * limitations under the License.
  */
 
+import appPlugin from '@backstage/plugin-app';
+import { useAsync, useMountEffect } from '@react-hookz/web';
 import {
   coreExtensionData,
   createFrontendModule,
   identityApiRef,
   useApi,
 } from '@backstage/frontend-plugin-api';
-import { useAsync, useMountEffect } from '@react-hookz/web';
-import { createApp } from '../createApp';
-import { CreateAppOptions } from '@backstage/frontend-defaults';
-import appPlugin from '@backstage/plugin-app';
 
 // This is a copy of the CookieAuthRedirect component from the auth-react
 // plugin, to avoid a dependency on that package. Long-term we want this to be
@@ -68,41 +66,61 @@ export function InternalCookieAuthRedirect() {
 }
 
 /**
- * Creates an app that is suitable for the public sign-in page, for use in the `index-public-experimental.tsx` file.
+ * This module is intended for use in public sign-in page apps, in the
+ * `index-public-experimental.tsx` file.
  *
  * @remarks
  *
- * This app has an override for the `app/layout` extension, which means that
- * most extension typically installed in an app will be ignored. However, you
- * can still for example install API and root element extensions.
+ * This module is used to enable the public sign-in flow where the build output
+ * is split into one small publicly accessible app, and the full app protected
+ * by auth.
+ *
+ * This module overrides the `app/layout` extension, which means that most
+ * extension typically installed in an app will be ignored. However, you can
+ * still for example install API and root element extensions.
  *
  * A typical setup of this app will only install a custom sign-in page.
  *
  * @example
- * ```ts
- * const app = createPublicSignInApp({
- *   features: [signInPageModule],
- * });
- * ```
+ *
+ *#### In `index-public-experimental.tsx`
+ *
+ *```ts
+ *import { createApp } from '@backstage/frontend-defaults
+ *import { appModulePublicSignIn } from '@backstage/plugin-app/alpha';
+ *import { appModuleSignInPage } from './appModuleSignInPage';
+ *
+ *const app = createApp({
+ *  features: [appModuleSignInPage, appModulePublicSignIn],
+ *});
+ *```
+ *
+ *#### In `appModuleSignInPage.tsx`
+ *
+ *```tsx
+ *import { createFrontendModule, SignInPageBlueprint } from '@backstage/frontend-plugin-api';
+ *
+ *export const appModuleSignInPage = createFrontendModule({
+ *  pluginId: 'app',
+ *  extensions: [
+ *    SignInPageBlueprint.make({
+ *      params: {
+ *        ...
+ *      }
+ *    }),
+ *  ],
+ *})
+ *```
  *
  * @alpha
  */
-export function createPublicSignInApp(options?: CreateAppOptions) {
-  return createApp({
-    ...options,
-    features: [
-      ...(options?.features ?? []),
-      // This is a rather than app plugin override in order for it to take precedence over any supplied app plugin override
-      createFrontendModule({
-        pluginId: 'app',
-        extensions: [
-          appPlugin.getExtension('app/layout').override({
-            factory: () => [
-              coreExtensionData.reactElement(<InternalCookieAuthRedirect />),
-            ],
-          }),
-        ],
-      }),
-    ],
-  });
-}
+export const appModulePublicSignIn = createFrontendModule({
+  pluginId: 'app',
+  extensions: [
+    appPlugin.getExtension('app/layout').override({
+      factory: () => [
+        coreExtensionData.reactElement(<InternalCookieAuthRedirect />),
+      ],
+    }),
+  ],
+});
diff --git a/packages/frontend-defaults/src/alpha/index.ts b/plugins/app/src/alpha/index.ts
similarity index 90%
rename from packages/frontend-defaults/src/alpha/index.ts
rename to plugins/app/src/alpha/index.ts
index f9e45bdeec..8ffa92e8aa 100644
--- a/packages/frontend-defaults/src/alpha/index.ts
+++ b/plugins/app/src/alpha/index.ts
@@ -14,4 +14,4 @@
  * limitations under the License.
  */
 
-export { createPublicSignInApp } from './createPublicSignInApp';
+export { appModulePublicSignIn } from './appModulePublicSignIn';
diff --git a/yarn.lock b/yarn.lock
index 9b0a90acec..a336f69e8d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -4743,15 +4743,18 @@ __metadata:
     "@backstage/core-components": "workspace:^"
     "@backstage/core-plugin-api": "workspace:^"
     "@backstage/dev-utils": "workspace:^"
+    "@backstage/frontend-defaults": "workspace:^"
     "@backstage/frontend-plugin-api": "workspace:^"
     "@backstage/frontend-test-utils": "workspace:^"
     "@backstage/integration-react": "workspace:^"
     "@backstage/plugin-permission-react": "workspace:^"
+    "@backstage/test-utils": "workspace:^"
     "@backstage/theme": "workspace:^"
     "@backstage/types": "workspace:^"
     "@material-ui/core": "npm:^4.9.13"
     "@material-ui/icons": "npm:^4.9.1"
     "@material-ui/lab": "npm:^4.0.0-alpha.61"
+    "@react-hookz/web": "npm:^24.0.0"
     "@testing-library/jest-dom": "npm:^6.0.0"
     "@testing-library/react": "npm:^16.0.0"
     "@testing-library/user-event": "npm:^14.0.0"