No. Those aren’t something you can just buy from a random shelf next to a Red Bull fridge, they need to be rated by a regulatory body and fitted for each climber, so definitely something you’d need at ask a store consultant for. Also, they would include equipment similar to a scuba system, including a refillable tank, regulator, and mask. Not just a standalone canister you hold to your face when you need a boost.

Something like this:

And if you’re using it medical purposes (it does say “respiratory support”), you should only get it at the instruction of a doctor, because the majority of people don’t need it and will be throwing their money (and a bunch of disposable canisters) away. Whereas the marketing for this is clearly “you, YES YOU, need this!”

And a proper medical oxygen system that a doctor might prescribe doesn’t look like that either. It would also have a complicated regulator, and would also be refillable, so you don’t have to go through can after can every day because you need it to live.

Or, for chronic need of supplemental oxygen, you wouldn’t even bother with a canister. Instead, a continuous oxygen concentrator would make more sense, which can give you fairly enriched oxygen from regular air and wall power, so you don’t need to constantly refill it:

(Source: My grandmother used supplemental oxygen for some time. We had one of those oxygen concentrators and I was always fascinated by it.)