While there has been the Libre RISC-V community-driven effort to create a RISC-V graphics processor that basically amounts to a RISC-V core with vector extensions/improvements and running a Vulkan software implementation (though they are now reportedly eyeing POWER instead of RISC-V), Think Silicon has announced the first actual RISC-V ISA based 3D graphics processor.
article: https://www.phoronix.com/scan.php?page=news_item&px=NEOX-V-RISC-V-3D-GPU