Weed was the original product from the Juul folks, back when the company was called Pax. Juul was a spin off from that company. The big attraction of Juul is to introduce teenagers to tobacco.
https://www.businessinsider.com/juul-e-cig-startup-marketing...
Anecdotally, they appear to be paying a ton of influencers on social media to advertise Juuls - friends notice it all the time, influencers that specifically almost all have children as their demographic. So they don't have to say they are directly buying ads targetting <18, but indirectly that's a huge amount of their reach.