Hello! Non-binary people are 100% included in the trans umbrella and someone using they/them pronouns or neopronouns would count as representation, as long as the character using those pronouns considers themselves trans :) (but that doesn't need to be additionally mentioned - I will just trust you on that, haha)
As for scifi/fantasy settings I'd say that if the character's gender or concept of gender goes against the patriarchal concept of gender in our modern society it definitely passes. A good example for this would be double trouble from the shera reboot. In the end we are no super strict on the rules, as they mainly exist to ward off trolls and people who didn't make their game with this jam in mind at all, and just submitted their game because the jam was open at the time. As long as you come in with the right intentions you don't have to worry too much :) Everyone has their own definition of what good trans representation/themes are after all.