That’s a good idea. Moving up the flashbacks to that section will give us a progressive exploration of Mando throughout the film. He’s a cipher that slowly gets filled in as the film goes on. As you said, it adds a strong character arc that ties together a more episodic narrative
I would personally keep the ambiguous ending about the heist crew though. I like the idea that we don’t fully know him or his morality by the end of the first episode.