No offense but trans-masc/trans-man headcanons about Arya are so incorrect, I'm sorry. I can't even take them seriously considering this fandom's desire to separate Arya from girlhood/womanhood. I would love it if people would stop trying to divorce female characters (and real women) from their identities as women just because they aren't traditionally feminine.

If we're talking about actual good-faith interpretations, ones that actually work with how Arya is written, then trans-femme is a much better fit. Arya has never had the desire to be a boy or be seen as one, she is fiercely insistent on her identity as a girl and corrects people several times, she doesn't consider herself a "real" Lady because she's not one in the same way her mother and sister are (!!!), she has self-esteem issues from her looks and ability to perform feminine tasks, she actually spends time pretending to be a boy but never considers herself one or enjoys doing it, as time progresses she loses the ability to pass as a boy (!!!), etc. Look at the material!! There's so much there to discuss from that perspective! Arya's non-conformity and how that fits into a society with such strict gender norms is fascinating and there's a lot to discuss there, but calling her trans-masc is one of the laziest interpretations to come up with.