what sorts of bras or other products to give the appearance of having breasts?
sports bras and bralettes seem to be the general consensus but holy shit there so many different kinds
The exact ones I got seem to be out of stock right now (https://a.co/d/cBeQUL2) but I found that they have space in them for inserts and I got a multi pack of padded inserts (like these: https://a.co/d/iKFhtq3) also and just put several in each, and that worked well enough for me. I don’t pass at all so it was mostly just for myself so it may not work for you, I don’t know. But that’s what I have done in the past.
Also I tried regular back and racer back and just happened to find the latter more comfortable. I think it’s just about what fits your body the best. I don’t have a lot of experience though. Probably others would have better advice.
does it look weird without the inserts?
I personally use sports bras with breastforms in the pad pockets. I think it's the best solution for me personally.