I'd like to see this in ED. It might benefit performance without all the SteamVr hoops (and their background processes) to jump through and just being able to fire up WMR natively.
From reading about OpenXR, it seems a good solution for software developers as the likes of Oculus and WMR (don't know about other brands) already adopted it. With it being open source, it could be the way forward to enable games to be played on any HMD, with no extra coding having to be implemented.