You should be able to fit into 4t-5t pullups. Snug, but will hold.
You may be able to fit into easy-ups too but due to their design the sides will likely give way after a short time. Old easy-ups before they merged with the feel'n learn line seemed more amenable to stretching. Feel'n learn & the newer post-merge easy-ups don't like being overstretched.
Some of the store brand pullups are rebranded huggies with different designs so they would also fit (Target,CVS). There are others (Playskool Little Tykes, Walgreens) that are an independent design. Dunno if Walgreens has switched or not but I thought I saw packaging and characters change; I may be getting confused with Rite-Aid's character & packaging change though. Playskool seems to be completely independent. Nice design, ample padding, and pretty durable and resistant to tearing. Drawback is they are not as stretchy as some of the others. At its limit the waist doesn't tear it just doesnt stretch anymore, similar to a bungie cord at it's limit. I can get them about 2/3 to 3/4 of the way up my legs before they hit their limit and my waist is currently around 38" or so.i never measured what that stoping point was and not going to right now since it's after 3am and I should actually be sleeping.
Nite-nite!