Is ZERO nicotine vaping, ok before and after BA and TT?

it is not “dangerous” to do zero nicotine vape. But it is dangerous to inhale unknown oils and substances into your lungs. It is unknown what effects the materials can have on your delicate tissues that are recognized delivery mechanisms to your heart, liver,brain and kidneys. Bottom line?
Don’t vape, just the regular air is dangerous enough.

As you are aware, Nicotine in any form - cigarettes, smokeless tobacco, gum, or e-cigarettes is bad for wound healing and since good plastic surgery depends on having nicely healed wounds, nicotine and plastic surgery really don't go well together. I have had multiple patients use nicotine-free vaping solutions as a bridge to stop smoking before their surgery and while I always encourage them to stop all of it prior to surgery, some have confessed after the fact that they kept using them. I can't say personally that I have seen any difference, while smokers who say they stop but don't have a greatly increased incidence of problems in my experience.
However, please don't take this as an endorsement of vaping nicotine-free solutions before your surgery, because as you are finding out, no one really knows at this point and it is all conjecture. I also think that a lot of vaping stores may be selling solutions that if not outright containing nicotine when they are supposedly "nicotine-free" may have other chemicals in them with unknown effects on your surgery. A lot of what constitutes a a good surgical experience is purely in the feelings, and it's not a good feeling to have lingering doubts during your recovery that you are doing something you shouldn't be doing. It's just not worth the mental machinations - your mind should be focused on doing the things you are supposed to do in your recovery, not worrying about things you feel you shouldn't be doing. Regardless, best of luck and wishes for a good recovery in your upcoming procedures!