I've been running my signet ln node on an RPI4 and ZFS on external SSDs for quite a while now. With bitcoind and elementsd. Stable as a rock with uptimes ranging from weeks to months - depending on system updates needing reboots. No Umbrel, though. Just Void Linux.

But, a silent pc may be for you. Just a few multiples in price for a good one. MeLE Quiter systems may be to your liking. I recently set one up for some stuff, also with a Void Linux base. Works well thus far.