As mentioned a few times in this comment section, this article covers the subject pretty well: https://ascmag.com/articles/the-mandalorian. All in all, it looks like many shots were truly captured at or near final, without significant post-production modifications.
Yes, I posted that myself :-) It was 2-3 months ago that I read it fully though. Favreau says "A majority of the shots were done completely in camera". However, any shot that included the ceiling screens needed VFX work to cover them, and that alone must have been a lot of shots.
It was for was shot composition as well; the cinematographer could see how it would end up while shooting. The screens updated to match the camera position in real time (e.g. to show the rest of a spaceship whose door was a physical prop).