A good use for Macs once the latest version of MacOS they will run is no longer supported. Install Linux and keep using it.

I went Linux two years go and won't go back, brought my family with me. I was glad for Ubuntu until finding Tuxedo OS which uses KDE Plasma, the best desktop environment: pretty by default, lots of options to shift it, familiar intuitive like Windows before. If curious, Fedora KDE is probably the easiest install to start with, or else try Tuxedo or OpenSuse Tumbleweed, all using Plasma desktop. Tuxedo and Fedora can both be run from usb stick without installation to try out, see if all drivers load, all works fine though a bit slower from stick than SD or harddrive.

My little boy uses Linux Mint, also a good starter OS.

I've been using Linux since 2006. I started on Ubuntu with Gnome 2, now I use Linux Mint with Mate. There are many different Linux distros and many different desktop environments. You can try them all if you want to.

from what I've heard of an iniative that sets up older devices, people are pretty happy with Mint as it's closer to the original Windows world of a decade ago and pretty easy to handle.

You can get Mint with Mate or Cinnamon. I prefer Mate because the look and feel are very similar to classic Windows. It's familiar and simple, and that's how I like it. To make it even more like classic Windows, I install the Clearlooks theme, move the taskbar to the bottom of the screen, and add Window List to the taskbar.

I had an old laptop, only got it in 2018 and it shouldn't be too outdated but for some reason no matter what I did it was stuck at 100% system usage.
Decided to give it a wipe and try out Ubuntu and now the thing is damn near back to it's glory days.