Seeing a Harry Potter who grew up in America before getting his Hogwarts letter changes the entire vibe of the foundational fish-out-of-water story. Instead of just being unfamiliar with wizard culture, he's coming from a whole different national and social context—maybe he's more assertive, used to a different school system, or has a distinct set of pop culture references. I read one where he was a skateboarder from California, and his complete lack of awe for Hogwarts' archaic traditions constantly baffled Ron and Hermione. The Sorting Hat might have a real challenge; that American individualism could easily push him toward Gryffindor, or maybe a Slytherin with a more entrepreneurial, self-made attitude. The central conflict with Voldemort could shift, too—an American-raised Harry might question the UK wizarding world's passive acceptance of pure-blood ideology far more openly and early on, potentially altering his relationships with key allies like Dumbledore, who values a certain kind of humility.
Where it gets really interesting is in the smaller character moments. How would an American Harry react to the food, the slang, or the complete lack of something like baseball? Would he try to introduce Thanksgiving? It's those cultural disconnects that writers can have a lot of fun with, making the familiar setting feel fresh again. The journey becomes less about discovering magic exists and more about navigating a clash of cultures within the magical world itself. I've seen some stories use it as a lens to critique the insular, classist nature of British wizarding society, which is a pretty clever angle that adds depth beyond the usual stations of canon.