Sticky bottom sheet

main.dart

import 'package:flutter/material.dart';

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: darkBlue,
      ),
      debugShowCheckedModeBanner: false,
      home: const Scaffold(
        body: Page1(),
      ),
    );
  }
}

class Page1 extends StatelessWidget {
  const Page1({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: StickyPageWrapper(
          child: Container(
        color: Colors.white38,
        child: Center(
            child: ElevatedButton(
          child: const Text('Go to page 2'),
          onPressed: () {
            Navigator.of(context)
                .push(MaterialPageRoute(builder: (context) => const Page2()));
          },
        )),
      )),
    );
  }
}

class StickyPageWrapper extends StatelessWidget {
  final Widget child;
  const StickyPageWrapper({Key? key, required this.child}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    var size = MediaQuery.of(context).size;

    return Stack(
      fit: StackFit.expand,
      children: [
        child,
        Positioned(
          left: 0,
          bottom: 0,
          child: Hero(
            tag: 'bottom_sheet',
            child: Container(
              color: Colors.orange,
              height: size.height / 4,
              width: size.width,
            ),
          ),
        )
      ],
    );
  }
}

class Page2 extends StatelessWidget {
  const Page2({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: StickyPageWrapper(
          child: Container(
        color: Colors.white38,
        child: Center(
            child: ElevatedButton(
          child: const Text('Go back to page 1'),
          onPressed: () {
            Navigator.of(context).pop();
          },
        )),
      )),
    );
  }
}