Mike McMahan has made crazier things happen working with Rick and Morty on inter-dimensional cable episodes, so I have faith even the craziest cameos are possible with his creativity.
The actor has danced around coming back, and Star Trek: Lower Decks could be the perfect opportunity to do so.
Obviously, the timelines are a bit problematic, but maybe a Starfleet worker stumbles across some documentary on Captain Kirk with interviews?
Hell, there could even be a chance to bring William Shatner back into the fold.