The most interesting "alternative" VR Desktop I've seen is a prototype a few years ago from the
ARCAN display server project:
https://arcan-fe.com/2018/03/29/safespaces-an-open-source-vr-desktop/
It's a bit dated now, and it's still very firmly in the "infinite terminals" category. But the plan9 inspired, "GUIs are just another stream you can pipe" idea, seems like a concept very amendable to VR.