I have an M2 SSD in a usb-3 enclosure. I am testing out if I can boot it on various machines, in which case I have the ultimate in server portability. I can then upgrade to a USB4, whenever those are released.

It has a ubuntu server/full node on one partition, umbrel on another, and linux mint gui with all of it's niceties. It's probably not the most secure setup though, as it isn't encrypted yet. I'm working on figuring out LUKS2.

So far most modern BIOS have had no trouble booting EFI on external drives. If one does, I can convert it back to mbr boot.