The WebView of QML is not provide WebChannel support. In the Qt example, it is suggest using WebSocket with WebChannel to implementation the connect of QML and HTML, the example needs start a websocket server in QML side, but the Android WebView is disabled to connect non-secure websocket in the "https" website, so if you need to use the WebChannel on Android, you must create a secure websocket server in QML side, this is a hard job.

I suggest add a "webChannel" property in WebView on all platforms, this is like WebEngineView.