Boba Fett obviously had no problem working for the Empire. As he told Din Djarin, he has no code he subscribes to. Boba’s career has been as a mercenary, willing to take money from anybody willing to pay his fee, similar to how Djarin was at the beginning of “The Mandalorian.” They both showed a willingness in the past to work with the Empire despite their status as foundlings (or in Boba’s case, the son of a foundling).
Djarin’s relationship with Grogu has moved him considerably in an anti-Empire direction, and Boba even joined him to mount an action against the remnants of the Empire (soon to evolve into the First Order). So Boba probably wouldn’t be welcomed back with open arms. On the other hand, his skills would help the First Order overlook this betrayal. Though if he starts working for the Empire/First Order, perhaps at some point Boba and Din will cross paths as enemies. Given their first brief skirmish when Boba first finds Din, we can only imagine how amazing a full battle would be.