Wow, VR Plasma sounds cool !
Yeah, it seems despite the best intentions, GPL doesn't always encourage open-sourceness... That sucks. Last I checked the guys developing Dolphin were running in the same issue too.
(It's also worth noting calling "OpenVR" a completely closed source system is rather moronic from Valve's part, although that's another issue.)
Hmmm... Wouldn't OSVR
be an alternative ? Although it seems more focused towards integrating custom HDMs with SteamVR, so might be unrelated...
Didn't even know about OpenXR until today, but it sounds like a great initiative from Khronos.
(... Seriously, VR acronyms are getting confusing. OVR, OpenVR, OpenXR, OSVR...