For good reason. Last time I checked (this year), Alyx crashes Mesa (i.e. your Vulkan layer) when the player enters an in-game load zone. This happens with native linux and the proton windows version.

So it doesn't work on Steam Machine, and also won't work when streaming from it to Steam Frame :(

I don't have a windows machine for that. A bit disappointing.

Well, I think the issue is in the AMD GPU driver. So, presumably it works on the Frame natively? Surely... Right?

It doesn't just crash Mesa but freeze the entire GPU last I tried. Kinda surprised that Valve has cared so little to fix this considering how much effort they have been putting in those drivers and into the game in the first place.

Ah, definitely a subtle reference to Black Mesa. Bravo Valve.