I'm a 6'1" man with size 3 feet which means every time they measure my feet at a shoe store, the Brannock device tells me I'm not a man
I was born with feet in the 1st percentile of the population and they stayed that way even despite getting taller. Now every shoe shopping experience is awkward af.
I'm on the opposite end as OP, I wear size 14. They are very hard to find since most manufacturers and shoe stores only go up to 13, and a lot of the ones that go to higher have a very limited selection in larger sizes. I would imagine it's similar at the lower end of shoe sizes.
Yes can confirm it's very hard to find age appropriate shoes in my size. Most are Velcro or have glitter or superheroes on them which is fine - I definitely have some of these as "house shoes" but finding proper dress shoes or boots is very tricky. Running shoes are also difficult to find as I'm below the threshold for women's sizes.
Same problem here with size 13. Most stores maybe have a couple available in my size so I mostly just wear Nike since they consistently have my size available.