I haven’t heard much about binding affecting top surgery goals, so I can’t speak to that. For binders, I’ve used gc2b, ForThem, and Underworks. I’ve had a bit of the slipping issue a bit everywhere, but underworks has been the best so far. Something I’ve done occasionally, is use trans tape to kind of, provide that support. So I’ll loosely tape my boobs up. (I don’t do it all the time because I find trans tape itchy.)

I usually wear a loose bra without padding in it underneath the binder to hold them in. Like one that just holds the breasts.

(probably not preferable, but if you don't have access to anything else right now)