It is at least theoretically possible to build a headless "GPU" from RISC-V processors that have the vector extension (RVV). RVV had been designed to be able to run programs compiled for the SIMT execution model that most GPUs use.

This Orange Pi RV2 has a small vector unit in each core, and could be used for at least prototyping the software until more powerful chips are available.

BTW. There have also been a couple hardware startups that have been working on commercial GPUs based on RISC-V's vector extension, with their own GPU-specific instruction set extensions for texture lookup and the like.