Oh nice! kinda funny story : I wanted the exact same thing as you a while ago so I used 'inhaler usage' on apple health app as a proxy for cigarette counter.

Also i know cigarettes & vapers do not always mix, but man I do always dream of creating a vape that can be set to a limited number of puffs/hour. It's probably the only way of actually controlling it or at least warning you, like you mentioned.

But still, fun that we can make these apps so easily now!