Flutter - How to load a local HTML file in WebViewScaffold?

I am trying to load a local HTML file in my WebViewScaffold however I don't have a callback for onWebViewCreated that the plugin webview_flutter offers. I cannot use that dependency because I want access to the state listeners of the webview's callbacks that webview_flutter doesn't offer. Could anyone show me how to load a local file? This is my current implementation -

   final Set<JavascriptChannel> jsChannels = [
      JavascriptChannel(
          name: 'Print',
          onMessageReceived: (JavascriptMessage message) {
            print(message.message);
          }),
    ].toSet();
    
    void main() {
      WidgetsFlutterBinding.ensureInitialized();
      runApp(MyApp());
    }
    
    class MyApp extends StatelessWidget {
      final flutterWebViewPlugin = FlutterWebviewPlugin();
    
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          title: 'Flutter WebView Demo',
          theme: ThemeData(
            primarySwatch: Colors.blue,
          ),
          routes: {
            '/': (_) => const MyHomePage(),
            '/widget': (_) {
              return WebviewScaffold(
                url: selectedUrl,  // How to load a local file here?
                javascriptChannels: jsChannels,
                mediaPlaybackRequiresUserGesture: false,
                appBar: AppBar(
                  title: const Text('Widget WebView'),
                ),
                withZoom: true,
                withLocalStorage: true,
                hidden: true,
                initialChild: Container(
                  color: Colors.redAccent,
                  child: const Center(
                    child: Text('Waiting.....'),
                  ),
                ),
            },
          },
        );
      }
    }