Thanks!
Those example are very close be the scenario we looking for is, presenting the Login screen as the first screen to authentication for accessing the application. The UWP example shows the login screen as a popup. This is why we think the PageRender approach in iOS and Android can also be a good solution for UWP.
Overall, I think an "AuthenticatorPageRender" examples for iOS, Android and UWP can be very useful. (similar to Xamarin.Auth.XamarinForms.AuthenticatorPage).
Thanks,
Mano