As someone who looked hard into it, RISC-V doesn't really make sense for a GPU shaders, IMO. You'd have to change so many things about how the ISA works that you wouldn't get a benefit to using a common ISA. Stuff like how shaders are batched and dispatched, textures accesses make sense to be their own instructions, you want a larger register file on the scalar side, the memory barrier semantics are much more complex, etc.

RISC-V might make sense inside of the GPU accelerators though. GFX command list processing, DMA engines, and video codecs all make sense to be something like RISC-V.

Most of the GPU workloads these days are not graphics related. They are general compute vector machines. The RISC-V vector extension is based on Cray's ISA and meant to compete in this space.

Nvidia are supposed to be using RISC-V inside future GPUs.

Yes, as a replacement for their internal proprietary logic controllers which operate in the periphery.

That has nothing to do with the RISC-V ISA being the right choice for core functionality like shader cores.

AFAIU their RISC-V variant can also be proprietary, akin to FreeBSD based products such as Junyper or macOS

To replace their falcon cores in the places I talked about in my second paragraph.

I was just trying to point out that Nvidia seems to be a bit more positive about the idea than "it might make sense".