provider_loading.dart

class Something with ChangeNotifier {
  bool hasCompletedSomething;
}

class SomethingElse with ChangeNotifier {
  bool hasCompletedSomething;
}

class Loading {
  Loading(this.value);

  final bool value;
}

void main() {
  runApp(
    MultiProvider(
      providers: [
        ChangeNotifierProvider(create: (_) => Something()),
        ChangeNotifierProvider(create: (_) => SomethingElse()),
        ProxyProvider0<Loading>(
          update: (context, _) {
            return Loading(
              context.watch<Something>().hasCompletedSomething &&
                  context.watch<SomethingElse>().hasCompletedSomething,
            );
          },
        ),
      ],
      child: MyApp(),
    ),
  );
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    if (context.watch<Loading>().value) {
      return const CircularProgressIndicator();
    }
    return MaterialApp(
      
    );
  }
}