If you've got an older Mac or Macbook that stopped getting updates, and you feel a bit gutted since was actually a good machine before Apple neglected you, I've put together a bunch of links
here for the tools and links you need to get Monterey running. Don't forget to do a Time Machine backup first and use [Internet] Recovery if something goes wrong.
I put all these links on one page because I was referring to them a lot, but someone else might find them useful.