I recently got EmbassyOS up and running on another RPi (already got Umbrel too). It's free if you compile the source code.

For M1 mac users, I documented steps to build the OS image with couple gotchas along the way you might need to know about (there are some libs only available on Linux 🤷‍♂️ that's why damn VM... but it works).

Also, turns out "rsync" is great command for copying bitcoin data from one SSD to another over your LAN if you need to.. stash that in the bag of useful tricks!