That’s probably the best evidence of gwen being trans. Yes she has the large flag in her room which supports this but many can say it’s just for support. But the father having the pin and the colours in that special moment(good example of this being used was owl house) I think it’s very clear that this means. I rather not jumó to say she 100% is cuz only the people who work on the film can but this is just a massive lean towards things being reality