Microsoft's Dzn Mesa Driver Already Hits Vulkan 1.2
Microsoft engineer Jesse Natalie who has been leading the work on this open-source Mesa driver for implementing the Vulkan APIs atop the Direct3D 12 interface sent in the patches for exposing Vulkan 1.2.
There are some fixes to the Dzn driver as well as a few new features needed to get Vulkan 1.2 advertised. The current pass-rate is around 99.86% for the Vulkan 1.2 conformance test suite (CTS). However, this does depend upon some not-yet-available Direct3D APIs and not-yet-published WARP fixes.
In any case with this merge now in Mesa 23.1, it looks like by next quarter's release this driver should be working nicely for Vulkan 1.2 on Windows/WSL atop D3D12 host drivers. We'll see ahead of that next release if they manage to even get Vulkan 1.3 passing.