I don't think second hand vapor is going to affect your pets. I don't believe it "affects" too much of anything, given there have been a few reports of measuring the inside of (vaping) vape shop brick and mortars, where quite a bit of vape can be floating about. I also think (although I don't know too much about benzoic acid) that nic salts don't tend to be more harmful, just because they have been converted into a salt form. I do DIY with nic salts from a vendor that doesn't use benzoic acid, so I'd imagine some salt vendors aren't using benzoic acid, and there is an at home "conversion" method using citric acid although I don't know much about it (yet).
I can say our dog is fine, (and he's tiny, Chiwawah size honestly) and he suffers no ill effects. My son's dog (who was a smoking dog she still tries to eat every cigarette .... she finds) appears to enjoy my vape and always sits somewhere where she is near to it. Don't know if it's the smell, or whatever, but she also has not come to any apparent harm.
I think you may be overthinking it a bit, but if something about vaping starts to bother your pets, I suspect they will let you know (behaviorally) but I haven't really seen it or heard of it,, honestly.
Anna