For Cordova iOS and Cordova Android it is possible to create plugins that create native UI on top of your app - you just include the libraries in your plugin and execute their API. Example for Android InAppBrowser.
For Cordova Windows, the native code is HTML and Javascript, hence the InAppBrowser plugin also adds a standard HTML tag for a Webview (or even plain Iframe) to get the same effect.
But you can also create plugins for Cordova Windows that use C# or C++ native code via a Windows Runtime Component. A public example is the globalization plugin that uses a .winmd file to offer APIs to the Javascript code (source code for this). This works great and is pretty awesome.
Unfortunately all the plugins that I could find use this C#/C++ native plugin mechanism only to receive some method call, do something with the parameters and return some data. None of those open any windows or create any other GUI (that might for example be offered by an external C# SDK).
How can one create a plugin for Cordova Windows that creates User Interface with native (C#, C++) code? Is this possible at all?