I can’t find any recent information on Linux support for SteamVR from Unity, and I’m not sure where to ask. I know they had experimental support in at least one build earlier in the year, but apparently it was then disabled. It’s been many months since the last thread on this was posted, and it has since been locked.
In case you’re not trolling: no, Linux is just as up-to-date as Windows. Not sure where you got that idea. The kernel just got an update five days ago. SteamOS, Ubuntu, Solus, openSUSE, and even Android are all Linux based operating systems, though Android isn’t otherwise related to the others except by the kernel.
SteamVR for Linux isn’t out of beta yet, but it is usable for developers and hobbyists such as myself, provided you use Ubuntu (Valve’s only officially supported desktop Linux OS) and can follow these instructions to a tee.
Someone who doesn’t know anything about Linux… however, I must say that DirectX has far more features than OpenGL. If only Nvidia/Microsoft would stop being so proprietary…