Unraid would be a very good choice for someone who is reaching out and asking this question. Debian can do the same but I suspect it’ll be easier to setup and manage on unraid.
Jellyfin is easy enough to get going, and I have it my annual try but it still feels clunky. Compared to Plex the windows client just doesn’t feel up to the level where Plex is.
Also noticed in my 5 minute attempt that hdr support seems to be lacking still.
Love the idea of an open source media system but it has a long way to go still.
It’s all highly configurable and usage heavily depends on the quality profiles you choose. If you go for 4K content it ramps up pretty quickly, 720p not so much.