Linux Vulkan Pathtracing is now working as of the latest UE5.5 build. I’m using Fedora Linux Workstation with NVIDIA driver installed via official binaries from the nvidia website.
In order to get it working I had to offload SM5 (Target RHI from PLATFORM section of editor options) and load SM6 then restart UE.
Big thanks to the developers for fixing this. It is very much appreciated.