On Flutter go_router how to change only content of special container?

I have a page in Flutter which has 3 different elements header, sidebar and main_content. Sidebar contains some text buttons login, customer, manager etc.

When someone clicks on the button on the sidebar i want to change only the content of the main_content. I dont want to replace whole screen. I just want to replace the content of main_content with another widget.

I am not sure if it can be done using flutter package go_router. Or I have to use state management for this case.

I tried Go_router shell routes. But i think it is made for different purpose.

router config :

final GlobalKey<NavigatorState> _shellNavigatorKey =
GlobalKey<NavigatorState>(debugLabel: 'shell');

const String pageOne = '/pageone';
const String pageTwo = '/pagetwo';

final appRouter = GoRouter(
  initialLocation: pageOne,
  routes: [
    ShellRoute(
      navigatorKey: _shellNavigatorKey,
      builder: (BuildContext context, GoRouterState state, Widget child) {
        return MainPage(child: child);
      },
      routes: [
        GoRoute(
          path: pageOne,
          builder: (BuildContext context, GoRouterState state) =>
              const MainContent(lable: 'one'),
        ),
        GoRoute(
          path: pageTwo,
          builder: (BuildContext context, GoRouterState state) =>
              const MainContent(lable: 'two'),
        ),
      ],
    )
  ],
);

main page class :

class MainPage extends StatelessWidget {
  //child is the content of each page
  final Widget child;
  const MainPage({super.key, required this.child});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Row(
        children: [
          //SideBar
          Expanded(
            flex: 1,
            child: Container(
              color: Colors.blue,
              child: ListView(
                children: [
                  GestureDetector(
                      onTap: () => context.go(pageOne),
                      child: const Text('page One')),
                  GestureDetector(
                      onTap: () => context.go(pageTwo),
                      child: const Text('page Two')),
                ],
              ),
            ),
          ),
          Expanded(
              flex: 2,
              child: Column(
                children: [
                  //Header
                  Container(
                    width: double.infinity,
                    padding: const EdgeInsets.all(16),
                    color: Colors.red,
                    child: const Text('Header'),
                  ),
                  //main_MainContent
                  Expanded(child: child),
                ],
              )),
        ],
      ),
    );
  }
}

main content class :

    class MainContent extends StatelessWidget {
  final String lable;
  const MainContent({super.key, required this.lable});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Text(lable),
      ),
    );
  }
}

run app :

    void main(List<String> args) {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      routerConfig: appRouter,
    );
  }
}

resault :