The “Nantucket Trilogy”, by S. M. Stirling is where I’d go for a role model character like you are seeking.
The first book in the trilogy is Island in the Sea of Time. The island of Nantucket is cast almost three thousand years into the past. Also along for the ride is a Coast Guard ship, the Eagle, captained by one Marian Alston. She is lesbian, black, and a ranker who climbed into the officer’s corps.
Captain Alston remains an important character throughout all three books, becoming head of island defense forces. She acquires a partner in the first book.
At one point, when the CEO of Nantucket’s civilian authority asks if her (adopted) daughters ever have problems because they have two mommies she says that mostly they don’t. This is because most folks have become tolerant, and she’s advised her girls that if anyone DOES tease them, then the two sisters should gang up and beat the snot out of the hecklers.
Do they have to be political activists on queer issues specifically? China Miéville’s* Iron Council* has a couple queer characters in Cutter and Judah, but they’re primarily socialist political activists, not gender rights ones.
Parrotfish (about a transboy) and Being Emily (about a transgirl) are both fairly recent YA novels.
Again, though, the characters aren’t particularly political or activist. What I liked about both of them was that they didn’t go for the “afterschool special” approach–both the boy and the girl weren’t ostracized or bullied.
I just got a request for a partial (first 30 pages of the MS) in the first week of querying the book as a work of fiction instead of positioning it as a memoir! Been thinking of repackaging it for awhile now.
The novel follows the lives of two Jewish cousins before, during, and after World War II. They are a Czech artist named Joe Kavalier and a Brooklyn-born writer named Sam Clay. In the novel, Kavalier and Clay become major figures in the comics industry from its nascency into its “Golden Age.”
Also Michael Chabon: “The Mysteries of Pittsburgh.” IIRC it’s a bit of a triangle with a straight guy dating a girl and then discovering he’s bi and having a relationship with a gay guy at the same time.