Its also plausible that Fett internationally gave his armor away to try to start a new life, right? Otherwise, why would he still be on Tatooine 5 years later?
At the same time, given who’s running this show, I wouldn’t be surprised if he is Rex (from Clone Wars). Rex has ties to Jango Fett and Ahsoka Tano, and reports had said he’s in this season, so it could make a lot of sense here.