Repurposing spare SBCs is my favorite part of self-hosting. I try to find a perfect fit for even the tiniest, underpowered computer in my collection. I have already dedicated one of my Raspberry Pi Zero 2W to host Vaultwarden and serve as an isolated, energy-efficient password manager.
The Pi Zero 2W is a perfect fit because it doesn't need a lot of power to work, supports wireless networking, and doesn't run out of memory while running the password manager. I have a few more Pi Zero 2W units, and I decided to dedicate another tiny yet frequently used tool to one of them.