How to return a value from a route dismissed by system back gesture. Will break predictive back in a root route, and maybe an antipattern overall.

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      initialRoute: '/',
      onGenerateRoute: (RouteSettings settings) {
        return switch (settings.name) {
          '/' => MaterialPageRoute(
            builder: (BuildContext context) => const PageOne(),
          ),
          '/two' => MaterialPageRoute<bool>(
            builder: (BuildContext context) => const PageTwo(),
          ),
          _ => MaterialPageRoute(
            builder: (BuildContext context) => const Text('404'),
          ),
        };
      },
    );
  }
}

class PageOne extends StatefulWidget {
  const PageOne({
    Key? key,
  }) : super(key: key);

  @override
  State<PageOne> createState() => _PageOneState();
}

class _PageOneState extends State<PageOne> {
  bool? result;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Page One'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            if (result != null)
              Text('Last result from Page Two was: $result'),
            TextButton(
              onPressed: () async {
                final bool? nextResult = await Navigator.pushNamed<bool>(context, '/two');
                if (nextResult != result) {
                  setState(() {
                    result = nextResult;
                  });
                }
              },
              child: const Text('Go to Page Two'),
            ),
          ],
        ),
      ),
    );
  }
}

class PageTwo extends StatefulWidget {
  const PageTwo({super.key});

  @override
  State<PageTwo> createState() => _PageTwoState();
}

class _PageTwoState extends State<PageTwo> {
  final TextEditingController controller = TextEditingController();
  bool value = false;

  void _pop() {
    Navigator.pop<bool>(context, value);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Page Two'),
        leading: IconButton(
          onPressed: () {
            _pop();
          },
          icon: const Icon(Icons.navigate_before),
        ),
      ),
      body: PopScope(
        canPop: false,
        onPopInvoked: (bool didPop) {
          if (didPop) {
            return;
          }
          _pop();
        },
        child: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              const Text('Go back to return the Switch\'s value to Page One.'),
              Switch(
                value: value,
                onChanged: (bool nextValue) {
                  setState(() {
                    value = nextValue;
                  });
                },
              ),
            ],
          ),
        ),
      ),
    );
  }
}