Question Hololens: How to place a 2D xaml UWP application in 3D AR space

My goal is: creating a setup with the Hololens and the digital Neosmartpen, where the user can sketch digital content on a surface and move this content around in Augmented reality. Through the hololens, a marker should be recognized and tracked and when recognized, a canvas should appear, bound to the marker (the marker will be put on a surface, which is printed with the Neosmartpen NCode Pattern).
Then sketches can be made, the output of these is seen through the hololens. When finished, the user can detach the canvas / the sketch from the marker and place it somewhere in 3D space.

So far I've created a working UWP xaml application that processes the data sent by the pen and displays it on a canvas. I created a Unity 2018 UWP project with .NET scripting backend (I know it's deprecated, but the Neosmartpen.SDK is .NET and i needed to use XAML and this seemed to be the only thing that worked). I moved my Visual Studio project to the UWP build path.
I can build and run the project in unity, which results in the UWP app being launched on my local machine. So far, so good. But now, i want to place this app in my scene, bound to a plane or a Gameobject or whatever is possible, so that i can make it appear through marker tracking. I don't have any idea where to begin.

Basically, how can i place the UWP Visual Studio application which is within my Unity Project as a 3D object in the scene.

Maybe someone is out there that can brainstorm with me or knows a solution.

Thanks in advance