Thanks all, these are very helpful suggestions!

Owala free sip is push to open. You have to also push the lid down to close.

Gatoraid
https://www.gatorade.com/bottles#shop-under-20

No opening, just squeeze a bit. I just keep filled up ones in the freezer and they stay cold all day.

The Yeti straw flip top would work for you.

we've got an insulated hydroflask with a "flex straw" cap. It's insulated, but lifting the straw up to sip from it is a bit tricky--it's just so stiff! so my son does it in two parts: first with his thumb and then straightens it up with his palm. For whatever reason closing it isn't as challenging.
Might also want to check camelbak or stanley "quick flip" and maybe owala's got one too.

Google adaptive water bottle. The blogger mom for Love That Max has a good list.

My 14 year old has mild cerebral palsy and is not really able to open water bottles that require unscrewing or anything that requires pushing/pulling in two directions or in a complicated way. He used to have a Thermos brand bottle that opened by just pushing a button in and it popped open, which was good, but it always came open in his backpack. Mostly he uses the plastic bike bottle type that you pull the top open/up with your teeth. I would love to get him an insulated water bottle (hot weather, all-day camp) that he can actually open himself, I think it would have to be by pushing a button. Any suggestions appreciated!