[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class WkWebViewPage : ContentPage
{
    public WkWebViewPage (string url, string title)
    {
        InitializeComponent();

        Title = title;

        App.GetWkWebView(this, url);
    }
}

public static class WkWebViewController
{
    private static WKWebView _wkWebView;

    public static void GetWkWebView(Page parentView, string url)
    {
        if(_wkWebView == null)
        {

    // INSERT ATTEMPTED APPROACHES BELOW HERE

            var frame = view.Frame;

            var cgRect = new CoreGraphics.CGRect(frame.X, frame.Y, frame.Width, frame.Height);

            _wkWebView = new WKWebView(cgRect, new WKWebViewConfiguration());

            view.AddSubview(_wkWebView);

    // NavigationDelegate is a custom class; not germane to the issue
            _wkWebView.NavigationDelegate = new NavigationDelegate();
        }

        var nsUrl = new NSUrl(url);
        var request = new NSUrlRequest(nsUrl);

        _wkWebView.LoadRequest(request);
    }
}

var renderer = Platform.GetRenderer(parentView);

            if (renderer == null)
            {
                renderer = Platform.CreateRenderer(parentView);
                Platform.SetRenderer(parentView, renderer);
            }

            var view = renderer.ViewController.View;

var window = UIApplication.SharedApplication.KeyWindow;

            var vc = window.RootViewController;

            while (vc.PresentedViewController != null)
            {
                vc = vc.PresentedViewController;
            }

            var view = vc.View;