[Build from source] React Native 0.81.4 Cannot build from source when following the doc

Description

Following this doc to build from source for React Native. But cannot run yarn android. I think I missed something from the docs?
package.json:

{
  "name": "AwesomeProject",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "android": "react-native run-android",
    "ios": "react-native run-ios",
    "lint": "eslint .",
    "start": "react-native start",
    "test": "jest"
  },
  "dependencies": {
    "react": "19.1.0",
    "react-native": "facebook/react-native#0.81.4",
    "@react-native/new-app-screen": "0.81.4",
    "react-native-safe-area-context": "^5.5.2"
  },
  "devDependencies": {
    "@babel/core": "^7.25.2",
    "@babel/preset-env": "^7.25.3",
    "@babel/runtime": "^7.25.0",
    "@react-native-community/cli": "20.0.0",
    "@react-native-community/cli-platform-android": "20.0.0",
    "@react-native-community/cli-platform-ios": "20.0.0",
    "@react-native/babel-preset": "0.81.4",
    "@react-native/eslint-config": "0.81.4",
    "@react-native/metro-config": "0.81.4",
    "@react-native/typescript-config": "0.81.4",
    "@types/jest": "^29.5.13",
    "@types/react": "^19.1.0",
    "@types/react-test-renderer": "^19.1.0",
    "eslint": "^8.19.0",
    "jest": "^29.6.3",
    "prettier": "2.8.8",
    "react-test-renderer": "19.1.0",
    "typescript": "^5.8.3"
  },
  "engines": {
    "node": ">=20"
  }
}

settings.gradle

pluginManagement { includeBuild("../node_modules/@react-native/gradle-plugin") }
plugins { id("com.facebook.react.settings") }
extensions.configure(com.facebook.react.ReactSettingsExtension){ ex -> ex.autolinkLibrariesFromCommand() }
rootProject.name = 'AwesomeProject'
include ':app'
includeBuild('../node_modules/@react-native/gradle-plugin')
includeBuild('../node_modules/react-native') {
  dependencySubstitution {
    substitute(module("com.facebook.react:react-android")).using(project(":packages:react-native:ReactAndroid"))
    substitute(module("com.facebook.react:react-native")).using(project(":packages:react-native:ReactAndroid"))
    substitute(module("com.facebook.react:hermes-android")).using(project(":packages:react-native:ReactAndroid:hermes-engine"))
    substitute(module("com.facebook.react:hermes-engine")).using(project(":packages:react-native:ReactAndroid:hermes-engine"))
  }
}

Steps to reproduce

1. Start a fresh project
2. Following doc from https://reactnative.dev/contributing/how-to-build-from-source
3. run yarn android

React Native Version

0.81.4

Affected Platforms

Runtime - Android

Output of npx @react-native-community/cli info

System:
  OS: macOS 26.1
  CPU: (10) arm64 Apple M4
  Memory: 538.31 MB / 24.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 22.12.0
    path: /Users/anh/.nvm/versions/node/v22.12.0/bin/node
  Yarn:
    version: 1.22.22
    path: /Users/abc/.nvm/versions/node/v22.12.0/bin/yarn
  npm:
    version: 10.9.0
    path: /Users/abc/.nvm/versions/node/v22.12.0/bin/npm
  Watchman: Not Found
Managers:
  CocoaPods:
    version: 1.16.2
    path: /opt/homebrew/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.2
      - iOS 26.2
      - macOS 26.2
      - tvOS 26.2
      - visionOS 26.2
      - watchOS 26.2
  Android SDK:
    API Levels:
      - "33"
      - "35"
      - "36"
    Build Tools:
      - 35.0.0
      - 36.0.0
      - 36.1.0
    System Images:
      - android-36.1 | Google Play ARM 64 v8a
    Android NDK: 27.1.12297006
IDEs:
  Android Studio: 2025.2 AI-252.25557.131.2521.14432022
  Xcode:
    version: 26.2/17C52
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.17
    path: /usr/bin/javac
  Ruby:
    version: 3.4.7
    path: /opt/homebrew/opt/ruby/bin/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.0.0
    wanted: 20.0.0
  "@react-native/monorepo":
    installed: 1000.0.0
  react:
    installed: 19.1.0
    wanted: 19.1.0
  react-native: Not Found
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found

Stacktrace or Logs

➜  AwesomeProject git:(main) yarn android                 
yarn run v1.22.22
$ react-native run-android
/bin/sh: react-native: command not found
error Command failed with exit code 127.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

MANDATORY Reproducer

https://github.com/kyunkakata/can-not-build-from-source-issue

Screenshots and Videos

No response

Start with the React Native source-build documentation and the mandatory reproducer, then compare its package.json and settings.gradle with the reported yarn android failure. Trace why the react-native command is unavailable and verify the documented setup against the provided environment. Done means a fresh project following the documentation can run yarn android successfully from the source checkout.