Possible, yes, but reimplementing the CUDA runtime and the official libraries and getting them up to par with the originals is a much bigger task than just doin

Possible, yes, but reimplementing the CUDA runtime and the official libraries and getting them up to par with the originals is a much bigger task than just doing the former and running Nvidias libraries in it. AMD did try to do a complete reimplementation of cuDNN with hipDNN but "last commit 5 years ago" doesn't inspire much confidence in it being competitive with cuDNN proper.