there are such devices - vaporizers, if you load a tobacco leaf into it, then you can evaporate it without carcinogenic smoke, but this is purely theoretical ... I have not tried it myself, and I have not met anyone familiar with it ... but I doubt their absolute harmlessness. .. tobacco leaf - it is different and with different nicotine content
As far as I know, modern electronic cigarettes can be filled with the so-called "slurry" without nicotine, these are sold along with nicotine. But if you are a supporter of the conspiracy theory and do not trust the sellers with the thought that they want to hook you on a harmful thing, then you can knead the mixtures yourself, there are a lot of instructions on the Internet. Although "hovering" without nicotine is practically the same as breathing over potatoes, there is little taste and nothing is felt.
The nicotine content does not depend on the electronic cigarette itself, but on the liquid that is used in it. The shops sell nicotine-free liquids in the same way as regular ones.