My experience has been that yes you can def find straight guys even if you are pre-op. I did experience a lot of rejection once I told guys that expressed interest, but that was probably half because I told them up front instead of waiting a few dates in, which I know if I waited till there was an actual connection some of those would have turned out differently. But... Idk, I just didn't want to mess with getting my hopes up. But then I realized that by doing it the way I was, I was basically filtering for guys that might be in to me just BECAUSE I'm trans, which was a depressing thought to me, because I don't really identify that way, so I kinda gave up.
But even doing it the dumb way I did, I still found several that didn't care. Ofc I decided that none of them were right for me, but I kind of think being able to make that decision was a priviledge. Like, I don't have to settle, you know?