Gallium's architecture of "state trackers" are sort of antithetical to the idea of Vulkan in many ways. Neither Intel's Vulkan driver, nor RADV, bother using it.
Gallium's 0.4 performance on my card is atrocious.
I am using MESA 13.0.6 on libDRM 24.68, and yet even Flare is damn slow. On current, it's much better, but Google's Street View is still slow, albeit gaming on PPSSPP is fast and good.. AMD/ATi RS 690 with MESA 20, I tried it, but I went back. Go figure. Even Quake ports are barely accelerated under the old MESA/KMS combo...