With VA-API supported on various Rockchip aarch64 chips as well as PCIe slots on several aarch64 SBCs/platforms, it’s possible to have AMD/Intel GPUs on ARM64 that support VA-API.
Could VA-API be built for Plex Transcoder on ARM64?
Edit:
Some libraries that may be required as well, for reference - https://github.com/jefflessard/plex-vaapi-amdgpu-mod/blob/master/Dockerfile