I think it depends what country you are in, rather than what you are actually doing. In the US, I find they are more inclined to say "excuse me" especially if they perceive you are in the way. In Canada and especially the UK, people are more inclined to say "sorry" in each of these cases. I also find that in Canada and the UK, people are more inclined to acknowledge that if two people bump into each other, both are probably at fault and so the polite thing to do is say "sorry" and move on without spending a lot of energy trying to assign blame to someone. In the US, I find that people are very loathe to acknowledge that they have made a mistake and so say "excuse me" meaning "you have done something wrong and I would like to get by". On the other hand, when an American is clearly in the wrong, they will apologize profusely. "Pardon me" is very formal and really should only be said to a judge in a courtroom! In the end, there is no real difference between the words, it is all about your behaviour and how polite you are perceived. Of course these are just my limited impressions.

A good option is just to say "Pardon me." This works in all of those cases. Here is a funny video that shows how to use it: https://www.youtube.com/watch?v=zy8W2w9IV-I

Sometimes I'll use both. "Excuse me. Sorry." I usually say sorry when I'm trying to get through somewhere narrow but I think part of it is because I feel like I'm in people's way. Some people just say excuse me in those situations. I think it depends on personality. I feel like saying excuse me when trying to get by somewhere small is more assertive. I realize that I don't necessarily have to say sorry but I feel compelled to.

You use «sorry» when you’ve made physical contact, by accident. You say «excuse me» when you’re in the way but haven’t touched them. 🇺🇸 English

When about to bump into someone I think sorry is better because it's like an accident and you don't mean for it to happen.