I'm not going to call this fanfiction, unless you want to make the argument that all literature is fanfiction of HKBH's Canon and I...okay, no, backtracking this.
Fanfiction has elevated the narrative stance where the story worth telling is not based on the level of conflict involved, but on the somewhat straightforward path from feeling less happy to more happy. Or the "someone give that cinnamon roll a hug" approach.
Fanfiction mostly does this because contemporary media (specifically for the screen) can be an absolute misery fest, especially for queer characters, and so fan-created content becomes a way to fight back against the tragedy that is the canonical lot and so the arc is from darkness into light, a pretty straightforward line up.
Ottoman's book takes the stories that are told about being queer in historical times, which are often an absolute misery fest, and writes a straightforward story about queer people falling in love and a world that just keeps getting better for them. Also having extremely good sex.
And that's the entire point; a fix-it-fic for a multiplicity of narratives that think that being trans in particular means being miserable. Anyway, it was extremely sweet.