Just wanted to say that it seems DXR is enabled by default in vkd3d version 2.11 https://github.com/HansKristian-Work/vkd3d-proton/releases/tag/v2.11

As you mentioned, you need the latest Mesa(ATM git master). With that I had no issues.

For ray tracing, the only thing which enables it for me is using the VKD3D_CONFIG=dxr11 environment variable, but it would get so slow in forest and around water that made me disable it.

GNU+Linux 😀