coughing works and most people don't seem offended by it

One MUP near me has signs instructing pedestrians to walk on the left and cyclist to ride on the right. So the walkers are FACING the cyclists and can more easily move aside.

I click my brake levers repeatedly, pulling on them slightly and releasing. The metallic clicking turns heads. Mostly i just roll by as far away from them as possible. So many headphones out there now that half the folks don't hear anything. Around toddlers and elderly I'm extra slow and gentle- it's their trail too and i'm happy they're out here.

Heloooo.........said loudly but not yelling. Followed by "hope I didn't scare you " as I go by.

Works for me, I gave up on bells. No MUPS around here and any pedestrians are walking on country roads. They seem to think a bell is some natural sound and rarely acknowledge it.

I click my brake levers too. I coast by toddlers with my right foot unstrapped and gear down to the little ring. I've had many occasions where just riding by causes them to weave across the entire path. When there's a group of people, I yell "ahoy" just because nobody expects a cyclist to yell it. I accelerate for dog walkers if they don't hear me approaching because the dog always will.

I generally don't say anything. As previously noted, people with earbuds or carrying on conversations are generally unreachable. In congested areas I pay close attention to the pedestrians and don't pass until I'm relatively sure of their trajectory. When someone ahead is hogging the whole path, I pull up behind them, slow down and loudly say "Excuse me." That usually works.