They also miss that on CUDA's case it is an ecosystem.

Actually it is C, C++, Fortran, OpenACC and OpenMP, PTX support for Java, Haskell, Julia, C#, alongside the libraries, IDE tooling and GPU graphical debugging.

Likewise Metal is plain C++14 plus extensions.

On the graphics side, HLSL dominates, following by GLSL and now slang. There are then MSL, PSSL and whatever NVN uses.

By the way, at GTC NVIDIA announced going all in with Python JIT compilers for CUDA, with feature parity with existing C++ tooling. There is now a new IR for doing array programming, Tile IR.