There is an FDA precedent for importation of medications from overseas. Basically, there is a "rule" that you are not going to get into legal issues from out of country sellers sending you three months or less of medication. Even if it's medication which is not FDA approved (although it can't be a scheduled substance.)
If it is over 3 months personal supply they can legally prosecute that person as some sort of "dealer" or "reseller." Otherwise, the package is turned back and you are sent a letter that says don't be expecting your "whatever." It also encourages you to NOT do it while also noting it is not a crime and they cannot legally order you to stop.
Depending on your seller, well, some will "guarantee" package arrival and will um, resend the medication (let's face it a lot of the time it's expired, sugar pills or whatever, they are losing little) unless you are able to identify the reputable drug companies which is EXTRAORDINARILY difficult as they are always changing their names.
I was willing to do it for a MEDICATION I could not GET because it was not FDA approved here and totally harmless. I also NEVER went generic.
I would have to go thorough an awful lot of vape gear before I were to get back into the "FDA Vape importation market." I also refuse to do it until I know the "rule" and the "law" because I break tanks like no one's business or I did so if I ordered 20 glass tanks and that is "too many" well ah, l would prefer not to be prosecuted for that.
The US does what it can to dissuade and annoy sellers, for example they can and will (most likely) block
fasttech's vape portion oft their site from the public that is fairly easy to do. They will also be vaguely threatening and etc. and offer up the kind of hassles FT won't want such as slowing down ALL packages more.
There is plenty the good old USA can do an FDA can do to be a right pain in the rear and I think they can say if something is banned here it is banned from overseas in this sort of non technical but deeply annoying way.
Good luck, I hope the FDA prove me wrong!
Anna