@puck if your not using your mac for any other purpose you may stick with it to see how it compete.

Even with a lot of services running, most of the time you don't need very high end cpu, especially if you can enable hw acceleration (like for jellyfin). In that scenario a 200$ power efficient small linux server might be enough (like N15 trigkey). What will cost you money is memory.

Don't forget you need to buy backups disks (or use the ones you already have).