They replaced most of the documentation with C++ examples, given the benefits the language has over C, that was already obvious to me in 1993.

As for the language extensions required by CUDA C, it is kind of interesting that clang and GCC extensions are praised and people keep referring to them as C, while everyone else's extensions are never C or C++ under the same measure.

With OpenAAC directives, an HPC industry standard, you can make use of plain old C11 with traditional #pragmas,

https://developer.nvidia.com/openacc

I used to like C++. Then it caused me headaches one too many times because of things it implemented that C did not have. Now I prefer to use C whenever I can, since it avoids entire classes of headaches that only exist in C++.