panfrost will allow for gpu acceleration. accelerated media decoding will occur in hantro and rkvdec and is not ready for chromium or firefox, which would rely on vaapi. from what i see things should be coming together in kernel 5.8, so not much more patience required.
also, mpv CAN use hardware decoding if you are using v4l2-request.
also, mpv CAN use hardware decoding if you are using v4l2-request.