yes of course!! i think nazuna being a trans man is a pretty common headcanon which also makes a lot of sense in the context of his backstory. when he was younger, people always praised him for being cute and pretty which did not align with how he saw himself at all + it also made him feel uncomfortable because he knew he was a Boy, and boys aren't Supposed to be cute and pretty. his looks, along with his beautiful (high-pitched) singing voice, were the only things that people really valued about him.. to the point that whenever he acted in a way that was in line with his natural (boyish) personality, the people around him would get annoyed with him, and he'd pretty much end up being forced to act cute against his will. but he always felt suffocated by it, and really just wanted to be accepted for who he really is.

i'd recommend reading the prologue of human comedy if you want to see his own thoughts on the matter! and the rest of human comedy and high five to see the resolution - how he's finally found people (ra*bits) who unconditionally love and accept every part of him, how he's managed to reclaim his own brand of "cuteness" on his own terms, and how his self esteem has improved enough that he can now truly be proud of the person he is.

as for the "het" part... honestly that's mostly just me thinking transhet hcs are cool and underrated. but i also just don't ship nazuna with any male characters or think he really shows any attraction to guys. and as for whatever shnz had going on in the past... well, shu is transfem to me so it still fits with the hc lol