Huh.

There’s a time and place for a DIY solution and academia can well be like that sometimes.

The latest Mac Mini can’t run Linux though. It’s M4 and asahi doesn’t even support M3 chips yet. But if you actually got the previous model with M1/M2 you can do Linux if desired. I might not attempt, and just use the Mac as a server as-is. It’s not too different from Linux. Asking the duck for “how to xx on Mac” when you already know the Linux equivalents should make your life tolerable.

Get base Debian, you’ll have more options for desktop environment. Once you get past the installation hassle it should just work for the rest of times. MX has its place but it’s specifically made to have no systemd which may not be something a new user is looking for. It feels very opinionated, is what I’m trying to say. May be your thing of course, but I’d recommend reading more on its philosophy before picking.

8 years is probably not old enough to require lighter desktops if the machines were at least mid range at the time. You should be able to use gnome or KDE as you please. Nothing against XFCE in principle, but it can be a little clunky especially for a laptop. No touch gestures, for example.