My first time alone I was wanting a real challenge, so I went to the most awful trashy redneck transphobic place you can think of. Walmart at primetime. I got all dolled up and decided the first thing I would do is head straight to the bathroom at Walmart during its busiest hours which was my biggest fear. I went in and had zero problems. Making my way back to the car because I forgot something, I came back and a gentlemen opened the door for me, I then decided I will head straight to the center of cis-ignorant rednecks, the gun section (to pick up some pepper spray lol) and nobody clocked me at all, in fact I had some guys smile at me and a few check me out. (being raised as a guy I can tell when I am being checked out.)
I then go down this gun aisle where all these dudes were in camo, and I was terrified but decided to just keep walking, I did a full circle and they looked at me and I couldn't tell what they were thinking. I go around a corner and could hear what they were saying and I heard them laughing and one said "I think she was lost." Which was off because I didn't think how odd it would be for a chick to be in that aisle, but that's what they noticed, not a trans girl but a female who didn't belong there.
Finally I decide that surely I cant be passable, there's no way, so I just keep walking around the store and didn't get clocked or ghosted or anything. I had a teenage girl stare at me weird but I don't know what that was about.
So that's what it was for me. Literally the most anti-trans, bigoted and gender binary place I could think of was at Walmart in Idaho where I live. Not only did I make it away but I spoke in my female voice a few times to employees and they didn't bat an eyelid and simply mam'd me.
Am I passable? I don't think so, I mean I had one guy at Costco walk by me and I heard him say to his wife "that's a man." and I was clocked a few times before, but its pretty rare. I have only been on HRT 3 months and am 6'1 and stocky and have a masculine face. I wonder if I'm passable or are people too terrified of me to pay attention? I don't know.
I have also had guy's do traditional gentlemen things for me like walk along the street side of a sidewalk when we cross paths, check me out without ghosting, opening doors etc. So I don't know, I am just trying to say to just dive in, it's a lot of fun and exhilarating when you make it out alive.
Another thing to note is that with a lot of people, their minds have no concept of trans or anything genderqueer that if you are presenting as a certain gender they will simply just assume that of you.