Any normal computer can become a “server”, its all based on the software.
Most enterprise server hardware is expensive because its designed around demanding workloads where uptime and redundancy is important. For a goober wanting to start a Minecraft and Jellyfin server, any old PC will work.
For home labbers office PC’s is the best way to do it. I have two machines right now that are repurposed office machines. They usually work well as office machines generally focus on having a decent CPU and plenty of memory without wasting money on a high end GPU, and can be had used for very cheap (or even free if you make friends that work in IT). And unless you’re running a lot of game servers or want a 4k streaming box, even a mediocre PC from 2012 is powerful enough to do a lot of stuff on.
Intentionally bad, if you buy Apple you’re supposed to use iCloud and never, ever leave the ecosystem.