MacLeech
The characters of Din Djarin (his name was never used) and Grogu were never introduced or explained why they were together. They expected the audience to know who they were.
All of that was explained at the very beginning of The Mandalorian series; this movie is just a continuation of the show. There were a lot of references to the series (i.e. the little paintball marker Grogu strapped to his wrist, the rhinoceros looking symbol on Grogu’s chestplate, why those little mechanic creatures called him a “bad baby”, etc.) If you’re going into this movie without ever having watched the series, there’s a lot you will miss, or probably will not understand.