That’s what PieFed changes though. You can still track how someone votes, but you can’t tie it to a specific profile (without doing some extra analysis and even then you can’t be completely sure).
Or, with my suggestion, you could track how that specific account votes, but it would be easy to obfuscate who exactly it is and (hopefully) impossible to track to the user’s other identities.
Considering those scanners usually register as keyboards and just do a dumb input “typing” it shouldn’t even be hard, lol.
The worst part would probably be picking a barcode scheme where the inputs make sense…