I've just tried out the UWP exporter and discovers it makes a JS-based UWP project. Having looked at it, Visual Studio 2019 and above will no longer support JS UWP projects.
The usual thing for UWP is to use C# UWP project, or C++/CX UWP project instead. The XNA exporter seems to use a C# runtime, so maybe it's possible to reuse a lot of the XNA code in a UWP C# project?
If it's written in something VS 2019 can open, it will be fairly easy to port extensions to UWP, as it would be a simple matter to extend the DarkEdif SDK to build for UWP via a C# interop wrapper.
Thanks for any info on the matter!