Upgrading to Ubuntu 22.04
It's silly to upgrade to a pre-release (heck, it's under serious development right now) version of Ubuntu, but it can be done.
Why did I do it? Because I wanted Emacs 27 (& Ruby 3.0!) and was too lazy to use backports or mess with snap.
Basically all you have to do is
sudo apt update && sudo apt upgrade sudo update-manager -d
Click 'Upgrade'. Wait.
Obviously you shouldn't do this on anything but a spare laptop or Raspberry Pi or virtual machine; nothing that has data on it that a) you care about and b) isn't backed up. P.S. You should always have backups!