CustomWebView.cs

public class CustomWebView : WebView
    {
        public void Cleanup()
        {
            _displayJSTextAction = null;
        }

        #region DisplayJSTextAction

        private Action<string> _displayJSTextAction;

        public void RegisterDisplayJSTextAction(Action<string> callback)
        {
            _displayJSTextAction = callback;
        }

        public void InvokeDisplayJSTextAction(string text)
        {
            _displayJSTextAction?.Invoke(text);
        }

        #endregion DisplayJSTextAction

        #region XFAppText

        public void SetXFAppText(string text) => Device.BeginInvokeOnMainThread(async () => await EvaluateJavaScriptAsync($"DisplayXFText('{text}')"));

        #endregion XFAppText

    }