I’ve done this via Wi-Fi, obviously, but a direct Ethernet-over-USB connection is something I never tried from an iPad, and it should also work with Lightning devices (and the right dongles). And its been possible for ages, so I’m partially kicking myself for never having tried it.
Would be nicer to do it via Bluetooth, though, and, in a perfect world, to something that was the same size as the Zero but with more CPU.and RAM–or, you know, to an actual UNIX userland inside the iPad…
Update: It was much easier than I thought to get Bluetooth PAN to work for Raspbian Stretch and Buster alike. here’s a gist with the required config, works great to SSH to
pi.local (which gets automatically announced via Rendezvous).