>vaguely remember some cartoon from the early 2000s about some teenage alien
>find out they had a fucking episode about non-binary gender
HOLY FUCK!!! I know that there were some kid shows back then that tried to sneak in LGBT themes like Hey Arnold, but it seems like western animation was trying to push this shit longer than we realized.
I feel like that's pretty innocuous though, if the show were made a few years later it might have been more in your face, but as it is I'd say it's pretty tame.