I have a 2012 Mac Mini. If you replace the slow internal HDD with a SSD it gives it a massive general speed boost. Maybe some extra ram will help as well. Both are easily replaceable.

I use it for retro gaming with OpenEmu on MacOS. But I’m sure there’s some good Linux distros for it.

You already answered yourself, use them as your !homelab@selfhosted.forum

You can start with an OS like YunoHost if you don’t feel comfortable. Next step, to mee, would be an immutable Linux docker machine with podman.

But YunoHost is already a good start and you can have a multimedia server, nextcloud or anything else (example, paperless ngx to scan, organize and store your important documents with OCR to search them)

I'd imagine the Mac mini could be turned into a retro gaming rig similar to retro pi or batocera (spelling?)

Replace the Mac mini drive with a cheap ssd.

If you have one of the early Mac minis, try the 32bit version of alpine Linux.

My pending project is to set it up as a old game server.

put weird linux distros on them and find something stupid to self-host for fun.

I personally would recycle them and buy/build something to fit my needs.

I recently bought a Mac mini specifically to selfhost Bluebubbles

the mac mini would be a great osx mavericks machine btw