A word of caution with this setup. A Raspberry Pi is not the most reliable hardware, and it is closed source (you don’t know what hardware back door it might or might not have). Also, Umbrel is not the most secure node in a package OS out there. I feel that Umbrel is in the camp of “move fast and break things” and likes to add a lot of apps onto their app store without too much scrutiny (scrutiny on the safety of these apps). As a result, be careful and be mindful of the amount of bitcoin you put on your Raspberry Pi running Umbrel. I would suggest that one should put on there the amount they are willing to lose; like how you would treat your phone hot wallet.

That said, I do run an exact same setup as you described above. It’s my secondary lightning node that I use solely for zapping, and I don’t keep too many sats on it. It has only one private channel opened to my primary lightning node where I keep most of my lightning sats.