Assuming you have already integrated the Scrimmage Rewards Widget into your Android application, you can listen to events emitted by the widget by adding a JavaScript interface to the WebView.

var message by remember { mutableStateOf("") }

// ...

AndroidView(factory = { context ->
  WebView(context).apply {
    // ...
    loadUrl("$url?token=$token")

    // Add the JavaScript interface to handle messages
    addJavascriptInterface(JavaScriptInterface {
      // Handle the received message
      message = it
    }, "Android")
    // ...
  }
})

Check out the Widget Events API for more information.