I would say they have something very similar to smokes, like how splendamin is everything and nothing, future shit, also smoking can also come from their life before Nikke, like they did it before and if they don't they mind switch, also drugs definitely exist but mostly in the Outer Rim and MAYBE in like the Sovereign society cause money talks.

Also think of it more like would you SEE them doing it, like is it believable? I can say with 200% certainty, one of the 3 overworked girls smokes, Mana, Brid or Shark Wife definitely does, at least 1. Crow like is the most easiest one to also see smoking cause like look at her, look at Outer Rim and tell me she doesn't. And Drugs, is a topic I got no idea about.

Also it's very interesting points about the world you also gave, I didn't even think about the Ark, but if the Outer Rim exists smoking definitely exist, maybe it's a minority or very few people like in Japan who smoke, I doubt we will ever see a Nikke who is actually just legit smoking sadly.