This is an AndroidManifest that implements Picture in Picture in Unity.

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.unity3d.player" xmlns:tools="http://schemas.android.com/tools">
  <uses-feature android:glEsVersion="0x00030000" />
  <uses-feature android:name="android.hardware.vulkan.version" android:required="false" />
  <uses-feature android:name="android.hardware.touchscreen" android:required="false" />
  <uses-feature android:name="android.hardware.touchscreen.multitouch" android:required="false" />
  <uses-feature android:name="android.hardware.touchscreen.multitouch.distinct" android:required="false" />
  <application android:extractNativeLibs="true">
    <meta-data android:name="unity.splash-mode" android:value="0" />
    <meta-data android:name="unity.splash-enable" android:value="True" />
    <meta-data android:name="unity.launch-fullscreen" android:value="True" />
    <meta-data android:name="notch.config" android:value="portrait|landscape" />
    <meta-data android:name="unity.auto-report-fully-drawn" android:value="true" />
    <activity android:name="com.unity3d.player.UnityPlayerActivity"
        android:theme="@style/UnityThemeSelector"
        android:screenOrientation="fullUser"
        android:launchMode="singleTask"
        android:configChanges="mcc|mnc|locale|touchscreen|keyboard|keyboardHidden|navigation|orientation|screenLayout|uiMode|screenSize|smallestScreenSize|fontScale|layoutDirection|density"
        android:resizeableActivity="false"
        android:hardwareAccelerated="false"
        android:exported="true"
        android:supportsPictureInPicture="true">
      <intent-filter>
        <category android:name="android.intent.category.LAUNCHER" />
        <action android:name="android.intent.action.MAIN" />
      </intent-filter>
      <meta-data android:name="unityplayer.UnityActivity" android:value="true" />
      <meta-data android:name="notch_support" android:value="true" />
    </activity>
  </application>
</manifest>