Adding to the chorus:

Headphones. I use full headphones, Sony something but I don’t recall the exact model, for two reasons: Firstly I find them more comfortable having over, not on, ear headphones. Secondly I find them to be better at noise-canceling than buds/plugs. When I was a kid I had simple construction headphones… not able to play music like my current set but was super-strong noise canceling.

Sunglasses. I used to be sensitive about anything being on my face… had to get over that 'cause pandemic but having done that I find Sunglasses help so much in cutting down unwanted visual stimulation.

Between that, and my phone, I’ve been able to avoid over-stimulation in public for years now. Normally I’ll let my headphones rest on my shoulders but wear the shades. If it’s too noisy I’ll put on the 'phones. If it’s still too noisy I’ll have them play music to down it out. If it’s still too much stimulation I’ll get out my phone and watch videos instead of play music to blot out as much as possible.

Don’t know if this’ll help but: I’ve found a useful stim for me is playing with, or comb/brushing, hair. So I let my hair grow out (and keep the unpleasant stim of hair on me at bay with a hat & scrunchies (scrunchies are better than normal hairties, they’re more durable and don’t pull as much removing them)) and grew out my beard. So I can fuss with a hair or two from my beard and I’m pretty sure nobody takes notice of it, at very least it’s not attention grabbing.

Also: On the subject of hats if the hair thing works, I’ve found ballcaps work pretty well on the hair-control front and the rim is quite practical for dealing with the Sun when it’s in annoying relative positions if you’re outside. Use to not be able to stand hats like this, the feeling of it on my scalp, but with my hair long it blocks that feeling entirely.