MTF here, so I don’t have full context/wisdom. I’ll try to articulate what I’ve gathered from my trans masc friends that aren’t on this platform.

I think it depends a bit on your chest size? If you’re on the smaller side and need something incognito you could probably get away with KT tape or other skin/body safe tape. Generally be a bit careful with tape. Pulling at skin too hard can cause irritation and even tears/splits. Skin can react to adhesives if left on for too long, things like that. A quick web search can go a long way here for checking out what works well.

For bigger chest sizes my understanding is that a good full coverage sports bra is the best option. Maybe shop a size down if you can stand it. Please do be careful though, too tight and you can hurt yourself. I know someone who would sometimes tape and use a sports bra to help position things so the sports bra did more flattening than holding up.

In my own itty bitty titty experience I have a bra from girlfriend collective that is fairly low stretch and I bought a size down in case I feel the need to be REALLY stealth mode.

Sorry to invade y’all’s space a bit, just an area I happen to have a bit of knowledge in! Best of luck! Stay safe! 💜 🏳️‍⚧️ ✊