The Xenogenesis Series by Octavia E. Butler

Humanity nukes itself out of existence and a colony of 3 gendered aliens swoop in, rescue the surviving humans, repair the earth and in exchange want to combine their species. each book explores a generation of the pact. It’s explores human nature, the nature of consent, gender and sexuality. Highly recommend it!

“The Long Way to a Small, Angry Planet” includes a few neat elements that you might be interested in.

There are species that change genders partway through their development, a species that has four separate sexes (including one that changes between the other three on a regular basis), a species that is nonbinary until they reach maturity. What we would consider ‘neopronouns’ are common.

There are also social and biological differences between races that are used to highlight other aspects of sex, gender, and body functions that us humans might not necessarily realize off the bat.

The Left Hand of Darkness by Ursula K. Le Guin immediately comes to mind as one of the most interesting sci-fi books I’ve read to deal heavily with biology and gender.

In the culture series humans can change their gender at will and there are some stories/parts of stories that deal with that and/or changing it. ALso dune has its whole sexual enslavement thing going on.

Octavia E. Butler - “Bloodchild” (short story)

James A. Tiptree - “The Screwfly Solution” (short story)

Samuel R. Delany - nearly everything he’s written

M. John Harrison - “Light”

Joanna Russ - “The Female Man” (curious how this holds up in 2023)

The Stars are Legion. This one is all about organic technology, with a twist that I don’t want to spoil. However, it’s a purely female civilization (necessarily lesbian, from our perspective). And the whole thing could be described as “dripping”.

I’m a cis-het male. While reading the book, I was dreaming about being pregnant with weird things, like kittens. It fucks with your mind! Excellent book.

I’ve just finished The Terraformers by Annalee Newitz.

I thought was an interesting discourse about urbanism, capitalism, gender and environmentalism. It fell a bit flat in parts, but the ideas around personhood and responsibility were thoughtfully done.

Bit late to answer, but Ursula LeGuin’s The Left Hand of Darkness is probably exactly what you’re looking for. Its about a visitor to a planet where the inhabitants are all one gender, and the societal differences that come from that.

All Tomorrows by C.M. Kösemen

It’s about humanities evolution over a billion years. It’s not specifically about gender/sexuality, but those topics do come up.