Try it! I have on both Minis (and G5) normal USB-PC-keyboards, which works fine (can reach OF-console).
Got hold of an older Apple USB keyboard here, which looks like it could be from an old Power Mac of some kind. Waiting for it to arrive in the mail.
Hopefully this will sort it out, or else I'll have to get a "new" MorphOS computer.
Member of Void - An Amiga demo group (website