With Ray Tracing becoming ever more popular, NVIDIA have written up a technical post on bringing DirectX Ray Tracing to Vulkan to encourage more developers to do it.
The blog post, titled "Bringing HLSL Ray Tracing to Vulkan" mentions that porting content requires both the API calls (so DirectX to Vulkan) and the Shaders (HLSL to SPIR-V). Something that's not so difficult now, with the SPIR-V backend to Microsoft's open source DirectXCompiler (DXC).
Since last year, NVIDIA added ray tracing support to DXC's SPIR-V back-end too using their SPV_NV_ray_tracing extension and there's already titles shipping with it like Quake II RTX and Wolfenstein: Youngblood. While this is all NVIDIA-only for now, The Khronos Group is having discussions to get a cross-vendor version of the Vulkan ray tracing extension implemented and NVIDIA expect the work already done can be used with it which does sound good.
NVIDIA go on to give an example and sum it all up with this:
The NVIDIA VKRay extension, with the DXC compiler and SPIR-V backend, provides the same level of ray tracing functionality in Vulkan through HLSL as is currently available in DXR. You can now develop ray-tracing applications using DXR or NVIDIA VKRay with minimized shader re-writing to deploy to either the DirectX or Vulkan APIs.
See the full post here.
Eventually, with efforts like this and when Vulkan has proper cross-vendor ray tracing bits all wired up, it would give developers an easier job to get Vulkan ports looking as good as they can with DirectX. This makes the future of the Vulkan API sound ever-more exciting.