To clarify some confusion, OpenXR Developer Tools for WMR was renamed to OpenXR Tools for WMR a few months ago, since many non-developers used it. It's exactly the same thing as before.
Here's a good read about the OpenXR apps from the MS store:
https://forums.flightsimulator.com/t/openxr-for-windows-mixed-reality-release-faq/489183