If you just need the binary data in the strings and can recover the boundaries between the individual strings easily, you could just write them to a file directly, as raw strings.
If you can’t recover the string boundaries easily, JSON seems like a good option:
a = [b"abc\xf3\x9c\xc6", b"xyz"]
serialised = json.dumps([s.decode("latin1") for s in a])
print [s.encode("latin1") for s in json.loads(serialised)]
will print
['abc\xf3\x9c\xc6', 'xyz']
The trick here is that arbitrary binary strings are valid latin1, so they can always be decoded to Unicode and encoded back to the original string again.