I'm trying to talk a lot of friends into using my. Jellyfin and even helped them set up tailscale and all that. But they keep going back to paying Netflix etc.
Also thought about that a lot. The most important is that your people can access your data. My partner and bestie both have LUKS keys on all of my devices.
Maybe do a test run with them to see if they can actually access it.
I would look at the AsRock Deskmeet.
Maybe not one of the current models but a generation before.
With that you can choose a CPU suiting your budget and you have the flexibility to add a used (or new) GPU in the future.