Yeah, had to mention vibrators or something else that was exclusively used on her is generally fine.
To be clear - this is not a sign of insecurity, not retroactive jealousy, either. This is just a simple wish to not interact with anything sexual used by the other guy I never chose to be intimate with and who can be gross to me, even if this is a pack of otherwise separate condoms. Like, it's not hard or expensive to replace - just buy a damn pack at the nearest pharmacy - and regardless of how much your partner cares, you won't lose anything either way. And I feel like I'm not the only person in the world caring for such matters.
I feel like as much as we try to make it less of a deal, this is just innately uncomfortable for many - not through insecurities it's often written off to, but rather through the nature of the intimate, of the highly personal. I want for our sex life to be ours alone in all aspects, not because someone else was "better" - I seem to be good and skillful and attractive - but because they, for all their previous experience with her, are not invited.
Also, heavily agree on vague answers and signs that partner is pressured. This is a no-go.
I have nothing against sex being "dirty, smelly, awkward, weird, funny, and stupid". I'm all for a natural passion that is not a refined picture, nor am I all puritan. In fact, I'd very much allow her to use my toothbrush and pillow should she want it (hot if I think about it), but I'd rather give her what pleases her best :D
I know someone has been there before, I just don't need to be reminded of that with items that were actively used in such process. And yeah, as a fairly monogamous keeper, I'd rather not have someone after unless there's a good reason for us to break up.
Also, yes, on your point, "no" means "no", and I'd rather have other words from her should we go full BDSM. This would otherwise introduce a lot of anxiety about hurting her, even if it's CNC.