I have had success with deploying the standard Plex docker and have it running with the " NVIDIA Container Runtime" this is run on a Ubuntu 18.04, 2.2ghz 64core 4x cpu & a Quadro p400 for GPU.
Currently I am able to run inside the container Nvidia-smi and my GPU shows up with Plex docker because I run it with the Nvidia runtime. (Note I was able to get Plex to use the GPU when running Plex on bare metal outside of docker)
This has all been good signs but I am still unable to get Plex to encoded or decode with the GPU. I have tried giving the Plex container privilege as well as specific device privilege for all /dev/nvidia Dev’s.
No luck so for any help guys would be great.