I think I wasn’t clear, for NVIDIAs you need to take some action, on some distros is ticking one box during installation, on others is installing the driver afterwards, but they work, all of my current computers are NVIDIA. Even without installing the proprietary drivers NVIDIA cards work fine for 90% of things, the problem is that gaming will have less performance and you wouldn’t be able use CUDA.
I know you’re googling it, but in any case AFAIK Plex can run on integrated cards, most cards can decode video nowadays so it shouldn’t be particularly hard. If you’re looking into using Plex I recommend checking Jellyfin, it’s an open source alternative, I’ve been using it for years and have nothing to complain about.