A curmudgeon's view: We've been to the Vatican Museum twice. The first time, we took an expensive, early morning tour. It was looooong. We followed a flag for four hours. Lots of info and exhausting. Last year, on our second trip, we booked our entry at the Vatican website and got audiotours. Due to COVID testing, (a necessary exercise on our last day there), we got a late start. At 1 pm, we breezed through the lines and got our headsets very quickly. Basically, we went where there weren't any crowds. We saw lots of areas that we hadn't seen on our first trip. If we saw something interesting, we plugged the number into the audiotour and listened specifically to that item. We had to go out and around to get into St Paul's but that was okay. On the streets outside the Vatican is where the cheap souvenirs are. Take your own headphone so you don't have to whole the audiotour up to your head the whole time.
Perhaps I'm a heretic but I find that a lot of the artwork the tour guides stop to expound upon aren't the ones that I find most compelling. La Pieta is beautiful but distant. I think the Sistine Chapel way overrated. Each time, I visit it hoping that it will speak to me but still find it crowded, loud and garish. . I think a lot of that is the masses of people. It's still worth seeing but don't expect an intimate experience. Sorry...