Most supermarkets don't sell smoking stuff, but you can get them at convenience stores and/or gas stations. A smoke shop is basically just a store devoted to nothing but smoking, usually for the specialty stuff since the places that do sell smoking stuff only have limited stock.
Anyways, from what I have seen the smoke shops here are open, at least their "open" signs are blinking. I never see anyone parked in front of them or shopping in them (and I don't smoke) so I wouldn't know.
Oddly enough, comic shops are considered essential as well, mine is still open although they haven't gotten any new comics from the distributors in almost a month.
How is a comic shop "essential" when bedding stores are forced to close even though people are forced to stay at home? ---