It did work with the Index at some point. Valve have been neglecting VR though (especially on Linux) so I wouldn't bet on it still working.

Considering the upcoming release of Frame, a VR headset based on Linux, I feel this couldn't be a more untrue statement.

The real truth is they moved out of the game development space and embraced the game platform space letting their old products wither and die.

Both can be true considering they are very different projects and hardware. SteamVR on linux even with a steam index has many issues. I am sure however that the linux support of the frame will be much better considering it also releases alongside there own Linux PC.

Ah, it predates SteamVR! Thanks, that explains why I didn't know about it.