Since at least https://github.com/keepkey/python-keepkey/commit/79854bfb82455751c667fdd525338a5a1e3b586c, the included pb2 files are build for python 2. `unicode` is undefined in python 3 https://github.com/keepkey/python-keepkey/blob/f0458664853aa7fbe0c31064d2cdda41cceec1b3/keepkeylib/messages_pb2.py#L464
Since at least 79854bf, the included pb2 files are build for python 2.
unicodeis undefined in python 3python-keepkey/keepkeylib/messages_pb2.py
Line 464 in f045866