In Ancillary, wasn't it the AI that was non-gendered, but not the society? I kinda liked that take (or at least that's how I saw it). I haven't read Terra Ignota, though.
The Left Hand of Darkness by Le Guin I thought did a good job at telling a story about a non-binary, literally gender-fluid society.
Octavis E. Butler's Lilith's Brood / Xenogensis series also does a good job telling a weird story about gender and aliens. Though it was a very challenging read (it hits some weird angles about consent and agency). Also, TCTTS's production group was/is looking at adapting this into a TV series.
The Left Hand of Darkness by Le Guin I thought did a good job at telling a story about a non-binary, literally gender-fluid society.
Octavis E. Butler's Lilith's Brood / Xenogensis series also does a good job telling a weird story about gender and aliens. Though it was a very challenging read (it hits some weird angles about consent and agency). Also, TCTTS's production group was/is looking at adapting this into a TV series.