Scales the whole screen in the scaffold so you work with Figma's units and enjoy const widgets at the same time

figma_compatibility_scaffold.dart

import 'package:flutter/material.dart';

class FigmaCompatibilityForBottomSheet extends StatelessWidget {
  const FigmaCompatibilityForBottomSheet({required this.child, super.key});

  final Widget child;

  @override
  Widget build(BuildContext context) {
    final mq = MediaQuery.of(context);
    final deviceWidth = mq.size.width;
    // const deviceWidth = 392.7; // common value for Android
    const figmaWidth = 375;
    final ratio = figmaWidth / deviceWidth;

    return SizedBox(
      width: double.infinity,
      child: IntrinsicHeight(
        child: FractionallySizedBox(
          widthFactor: ratio,
          heightFactor: ratio,
          child: Transform.scale(
            scale: 1 / ratio,
            child: child,
          ),
        ),
      ),
    );
  }
}

class FigmaCompatibilityScaffold extends StatelessWidget {
  const FigmaCompatibilityScaffold({
    required this.body,
    this.appBar,
    this.bottomNavigationBar,
    this.floatingActionButton,
    this.extendBodyBehindAppBar,
    this.backgroundColor,
    super.key,
  });

  final Widget body;
  final AppBar? appBar;
  final Widget? bottomNavigationBar;
  final FloatingActionButton? floatingActionButton;
  final bool? extendBodyBehindAppBar;
  final Color? backgroundColor;

  static const showThemeFabIfNoFab = false;

  @override
  Widget build(BuildContext context) {
    final mq = MediaQuery.of(context);
    final deviceWidth = mq.size.width;
    // const deviceWidth = 392.7; // common value for Android
    const figmaWidth = 375;
    final ratio = figmaWidth / deviceWidth;

    return FractionallySizedBox(
      widthFactor: ratio,
      heightFactor: ratio,
      child: Transform.scale(
        scale: 1 / ratio,
        child: MediaQuery(
          data: mq.copyWith(
            viewInsets: mq.viewInsets.copyWith(
              bottom: mq.viewInsets.bottom * ratio,
            ),
          ),
          child: Scaffold(
            body: body,
            appBar: appBar,
            bottomNavigationBar: bottomNavigationBar,
            floatingActionButton: floatingActionButton,
            extendBodyBehindAppBar: extendBodyBehindAppBar ?? false,
            backgroundColor: backgroundColor,
          ),
        ),
      ),
    );
  }
}