It seems the OpenGL over Vulkan driver, Zink, has been coming along at a ridiculously impressive pace. Open source consulting firm Collabora has given an overview on how it's doing.
As a brief reminder on Zink: "Zink is an OpenGL implementation on top of Vulkan. Or to be a bit more specific, Zink is a Mesa Gallium driver that leverages the existing OpenGL implementation in Mesa to provide hardware accelerated OpenGL when only a Vulkan driver is available." - Collabora.
Work on it has progressed so far that Zink can now expose the OpenGL 4.6 (Core Profile) feature set. However, it's not yet classed as a properly conforming driver for that, as they still need to go through the official Khronos Group conformance testing and pass it.
If you take a look over on MesaMatrix, Zink now covers all the listed OpenGL extensions. Collabora say, in theory, this means any OpenGL application / game should be able to run with Zink and have it technically run through Vulkan (like Steam games). Developer Mike Blumenkrantz, who was hired by Valve, is currently still hacking away on Zink and testing out games which Blumenkrantz has been regularly blogging about.
They're also now using Continuous Integration for testing, which means regressions and bugs should be caught quicker. They're able to do this using 'Lavapipe', a Vulkan software implementation in Mesa that reuse the rasterizer from LLVMpipe so they can run it all on virtual machines in the cloud.
Oh and early macOS and Windows support is also there now too.
Check the full blog post for more.