CUDA-Fortran is actually great. The added bits of syntax fit very well in the language, much better than standard CUDA in C or C++.

It’s a shame I never really was in a situation to use it in a real program (also, you had to use PGI, which I have always found sub par), but I have tinkered with it over the years and it is very pleasant to use.

There is also Intel oneAPI Fortran.