Check out BOINC: https://boinc.berkeley.edu/

Raspberry Pi I’m not sure if it’s worth it. But in short you can advance some science with spare CPU hours. Should be possible to limit it so it doesn’t heat up and use just a bit of the cycles depending on other load…

Cool nick! But it could be even better!

Good open source alternative: Fossify calendar or Etar with Davx5