I think there is a misconception here: CUDA is not even close to being C for assembly used by Nvidia's GPUs, PTX is, and it uses JIT to compile to Nvidia's GPU assembly, SASS. It honestly easier just to have LLMs write PTX directly than to go through CUDA C/C++ at all.
Again, "CUDA" isn't a programming language, it stands for Compute Unified Device Architecture; "C/C++ for CUDA" are the high-level languages that compiles to PTX and then SASS as well CPU orchestration code via NVCC.
And to be honest, pretty much everything you can do in CUDA C/C++, you can also do in HLSL/GLSL compiled to SPIR-V, as long as the Vulkan hardware extension is available.
Again, "CUDA" isn't a programming language, it stands for Compute Unified Device Architecture; "C/C++ for CUDA" are the high-level languages that compiles to PTX and then SASS as well CPU orchestration code via NVCC.
And to be honest, pretty much everything you can do in CUDA C/C++, you can also do in HLSL/GLSL compiled to SPIR-V, as long as the Vulkan hardware extension is available.