Many rehabs do allow vaping. My son's did (Sierra Tucson, and you could not believe the insurance wrangling that went on to get them to pay for it. They ended up having to as his first, cheapo rehab kicked him out for having a "dual dx".) Since there was no actual "dual dx" rehabs within network in state, I got to choose. Though I have to say rehabs for the "rich" (though S.T rep is slipping) have really different rules, and I was not impressed with some of them. For example, when allowing "visiting" I could have LITERALLY smuggled in the kid any drug I chose. While I'm sure the rehab felt that family and friends visiting wouldn't bring stuff in, they vastly underestimate the amount of codependency that goes on in some families, not to mention "friends." I did find it amusing in some ways, but vaping was totally fine. I think they required sealed e-juice and a receipt from a store, and they held on to the bottle but would fill it whenever.... Other rehabs I've seen out here recently adopted "no nicotine of any type" and I seriously did not know how on EARTH they were going to support that choice. Turns out staff just "ignored" the no-nic policy and would take smokers outside the facility to smoke, LOL.

Not sure if admin got wind of that yet.
Rehabs are the wild wild west still. I doubt you'll find the same set of rules (or treatment format) anywhere. I only sent my kid because at the time he was facing 15 years (got dropped to 4 after a charge was dropped due to no actual proof of it). I don't regret my decision, but I'm not sure my kiddo learned much. I was dragging him with me to AA meetings from the age of 2 onward. So, he clearly didn't learn too much *there" either, Haha. He wound up on probation, learned (and paid) a LOT, and just got his felony expunged. Way to go kid.
But I wouldn't have sent him to any rehab that disallowed smoking or vaping, that was one of my questions of the rehabs I contacted (during the 3 days I spent on the phone with Cigna, non-stop, LOL, I literally would awaken, grab cigarettes and coffee, and then call them. I think by day 3 they got the picture that I was NOT going away, LOL, and that I knew my rights, again, LOL. It was worth it (probably).
Anna