A standards-compliant one? It shouldn’t matter, right?
It was a really old Bluetooth 2.0 keyboard that I had lying around.
It is an interesting compromise between
sshing in from a regular computer with a full-size normal keyboard, and
b) using the on-screen keyboard.
Tab for ‘completion’ is certainly a lot faster and easier than using the on-screen keyboard. So if you are doing a lot of work in a shell, it is nicer.
One thing I should mention: The Librem 5 gave questionable information about the battery level of the Bluetooth keyboard, reporting it as ‘almost flat’ when I just charged it up fully before doing any testing. However before testing this keyboard with the phone, I tested it with a regular computer and the regular computer gave the same message. So either the keyboard’s battery condition is shot (possible since the keyboard has been sitting around doing nothing for some years) or this is a Linux problem in common.