Flutter: Force portrait UI on tablets (iOS + Android) even when device is landscape, but avoid letterboxing / black bars

I have a Flutter app that should be portrait-only on phones and tablets.

What I want:

• Even if the user holds the device in landscape, the app should stay in portrait UI

• I am not able to create a landscape layout

• I want the app to still look fullscreen (no black bars/letterboxing)

Current setup (Flutter):

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await SystemChrome.setPreferredOrientations([
    DeviceOrientation.portraitUp,
    DeviceOrientation.portraitDown,
  ]);
  runApp(const MyApp());
}

iOS Info.plist currently supports both portrait and landscape (iPad too).

Problem:

• On iPad simulator and some Android tablets, the app still rotates to landscape.

• If I remove landscape orientations, the app stays portrait but in landscape device orientation I get black bars / letterboxing (the portrait UI is centered with empty areas around it).

• I want portrait UI fullscreen even in landscape (no letterboxing). Like in some games or apps.

Questions:

1. Is it technically possible on iOS and Android to keep a portrait UI fullscreen when the device is landscape, without supporting a landscape layout?

2. If not, what is the recommended approach for tablets? (e.g. allow landscape but keep a portrait-like centered layout, or opt out of iPad multitasking, etc.)

Any guidance or platform limitations explanation would help.