Youth catchers mitt help

Id look at All Star (Many Models) and Akadema Preying Mantis.
I am grown and use a 33.5 so that sounds correct just eyeballing.

ETA: err on the side of too large if its close.

For a 10 year old, save money. At about 13, you'll be getting him a $200 mitt probably (A2000 or something)

I was always a fan of Mizuno mitts and gloves

Though I don't have direct experience with their mitts, I can't recommend Kelley USA gloves enough. I still own a Century Series 6-finger one (from the old CF days, now used for some slow pitch). A teammate also had an 11.5" I-web from the ProLine series that was a really sweet MI glove. Looks like the smallest mitt they make is a 32.5", though, so it may be a tad big for your little leaguer.

Other than that, I mostly caught with a hand-me-down Mizuno from my big brother (didn't start catching 'til 12 or so). I did have some problems with a recurring jammed thumb/popped vessel when catching off-speed stuff from a particular lefty, but I never had another mitt to compare it to to see if it was actually bad/inadequate padding or just simply user error. It was probably just user error. I wasn't a great catcher.