That I know of there’s only been one solution designed to render the Linux desktop in VR (not just Steam games) by Collabora called XRDesktop.
That number now becomes 2… the company Immersed has produced a VR app that can render the desktops on Linux, Mac, and Windows.
The caveats are unlike XRDesktop it only works on the Oculus Quest and Oculus Go but more HMDs are planned.
Only Ubuntu is supported but it’s packaged as an appimage so it may work elsewhere.
It doesn’t appear to adhere to software freedom and while the app is free for 2 monitors, there’s a pricing structure to unlock additional features like up to 5 monitors.
Though I haven’t tried XRDesktop yet (because I lack a HMD), Immersed’s software shows every sign of being far more user friendly and easy to set up. In part because XRDesktop is in alpha.
You can’t use an Oculus without a Facebook account as of Oct 2020
That said, I am VERY excited to see Linux desktop VR broadening and this is a promising sign for things to come. Thank you to Immersed for supporting Linux.