Although it technically isn't explicitly about trans people, Terry Pratchett's Monstrous Regiment explores a lot of ground about repressive gender roles and norms, feminism and the arbitrariness of religious doctrine. It does all of this while being absolutely hilarious and a joy to read.

It's also technically part of a series, but like all Discworld books can absolutely be read as a standalone book.

Maybe not an absolute top pick due to not cleanly hitting all your requirements, but I'd still recommend it.