You can get no nic cigarettes, at least you used to be able to but they're not made of tobacco, just a "random herb blend." They were disgusting, and they were combustible, but they're available now, you'd need a specialty cigar store and they might even need to order them for you.
They quickly convinced me of the disgustingness of smoking non-nic combustibles, I think I smoked about 3 of them. That said, I wasn't getting my nicotine/MAOI soup, just inhaling some rather flavorless smoke. I am unsure if there's a 0 nic tobacco product out there. I think you'd have to go to ultralights... but why would you? Curiosity? Hoping for a "safer" combustible? That doesn't exist in the BT planet though they are saying those IQOS things do, and it's a vape, but it does have nicotine in it. I would be scared, personally, of trying a BT product that might draw me away from vaping so I have no interest. Nor would I smoke 0 nic cigarettes, I already tried that experiment
Anna