diff --git a/packages/frontend-app-api/api-report.md b/packages/frontend-app-api/api-report.md
index fe0ceecbc6..0c6471480d 100644
--- a/packages/frontend-app-api/api-report.md
+++ b/packages/frontend-app-api/api-report.md
@@ -4,6 +4,7 @@
 
 ```ts
 import { BackstagePlugin } from '@backstage/frontend-plugin-api';
+import { Config } from '@backstage/config';
 import { ConfigApi } from '@backstage/core-plugin-api';
 <<<<<<< HEAD
 import { JSX as JSX_2 } from 'react';
@@ -20,24 +21,14 @@ export function createApp(options: {
 };
 
 // @public (undocumented)
-export function createExtensionTree(): ExtensionTree;
-
-// @public (undocumented)
-export interface ExtensionInstance {
-  // (undocumented)
-  readonly $$type: '@backstage/ExtensionInstance';
-  readonly attachments: Map<string, ExtensionInstance[]>;
-  getData<T>(ref: ExtensionDataRef<T>): T | undefined;
-  // (undocumented)
-  readonly id: string;
-}
+export function createExtensionTree(options: { config: Config }): ExtensionTree;
 
 // @public (undocumented)
 export interface ExtensionTree {
   // (undocumented)
-  getExtension(id: string): ExtensionInstance | undefined;
+  getExtension(id: string): ExtensionTreeNode | undefined;
   // (undocumented)
-  getExtensionAttachments(id: string, inputName: string): ExtensionInstance[];
+  getExtensionAttachments(id: string, inputName: string): ExtensionTreeNode[];
 }
 
 // @public (undocumented)
diff --git a/packages/frontend-app-api/src/wiring/createApp.tsx b/packages/frontend-app-api/src/wiring/createApp.tsx
index e5dc1db847..23b7b4ca11 100644
--- a/packages/frontend-app-api/src/wiring/createApp.tsx
+++ b/packages/frontend-app-api/src/wiring/createApp.tsx
@@ -15,7 +15,7 @@
  */
 
 import React, { JSX } from 'react';
-import { ConfigReader } from '@backstage/config';
+import { ConfigReader, Config } from '@backstage/config';
 import {
   BackstagePlugin,
   coreExtensionData,
@@ -84,29 +84,29 @@ export interface ExtensionTreeNode {
 
 /** @public */
 export interface ExtensionTree {
-  getExtension(id: string): ExtensionInstance | undefined;
-  getExtensionAttachments(id: string, inputName: string): ExtensionInstance[];
+  getExtension(id: string): ExtensionTreeNode | undefined;
+  getExtensionAttachments(id: string, inputName: string): ExtensionTreeNode[];
 }
 
 /** @public */
-export function createExtensionTree(): ExtensionTree {
+export function createExtensionTree(options: {
+  config: Config;
+}): ExtensionTree {
   const plugins = getAvailablePlugins();
   const { instances } = createInstances({
     plugins,
-    config: ConfigReader.fromConfigs(
-      overrideBaseUrlConfigs(defaultConfigLoaderSync()),
-    ),
+    config: options.config,
   });
 
   return {
-    getExtension(id: string): ExtensionInstance | undefined {
+    getExtension(id: string): ExtensionTreeNode | undefined {
       return instances.get(id);
     },
     getExtensionAttachments(
       id: string,
       inputName: string,
-    ): ExtensionInstance[] {
-      return this.getExtension(id)?.attachments.get(inputName) ?? [];
+    ): ExtensionTreeNode[] {
+      return instances.get(id)?.attachments.get(inputName) ?? [];
     },
   };
 }
@@ -116,7 +116,7 @@ export function createExtensionTree(): ExtensionTree {
  */
 export function createInstances(options: {
   plugins: BackstagePlugin[];
-  config: ConfigApi;
+  config: Config;
 }) {
   const builtinExtensions = [Core, CoreRoutes, CoreNav, CoreLayout];
 
diff --git a/packages/frontend-app-api/src/wiring/index.ts b/packages/frontend-app-api/src/wiring/index.ts
index 7eb1cc2de7..dc1ba3bc13 100644
--- a/packages/frontend-app-api/src/wiring/index.ts
+++ b/packages/frontend-app-api/src/wiring/index.ts
@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 
-export type { ExtensionInstance } from './createExtensionInstance';
 export {
   createApp,
   createExtensionTree,