Honestly, start small - buy some cheap hardware that supports NVMe - an old desktop, a raspberry pi 5, a latte panda… Then set it up as a server with your favorite Linux distro. If you’ve never done it before, stick with one of the big ones; Raspian, Ubuntu, etc. Get that up and running. Then install Jellyfin on it and test it out so you learn the stack.

Do you have eyes on something you would like to do past Jellyfin?