not sure what opencl-mesa is good for.... with opencl-mesa installed I can crash my system 100% certain running libreoffice with opencl enabled and also BOINC will report calculation errors. With opencl-amd both issues don't show up.
So at least for vega 10 opencl-mesa seems to be a bad choice. Maybe garuda-video-config could depend on opencl-driver instead of opencl-mesa? opencl-driver is satisfied by opencl-mesa and opencl-amd.