It's awesome that the Keepkey can U2F, but it can be improved:
the icon to press and hold button is shown yet a short tap already activates it (not sure whether that's intentional or not as all other instances of the icon I saw so far need it being hold down for a bit)
the idea to show the appid hash not directly but to use the first 44 bits to create a little mnemnoic is plain brilliant. why only during login and not signup?
flow when registering existing or authing non-existing credential: in these 2 scenarios ideally the device should tell you that it already is registered or that there is no handle it can serve. the current messages of signing up or logging in with the credential despite the opposite occuring is a bit confusing.