Heart's in the right place but can I just break down "biological gender" for a sec? Gender is more or less a Victorian euphemism for "sex". The word's original usage and origins are actually close to "genre" like book genre and in modern usage it works closer to "genre" as it describes an internal sense of affiliation to a cultural or phenotypic category or abstention from category drawn culturally broadly along reproductive groups. It's a fuzzy line that we don't use biology to try and police on purpose. It's more the realm of psychology and wrapped up in questions of what supports a fulfilling life of interpersonal connection.

Gender is a lot of things but if you are talking about sexual characteristics and intersex people it's important to distinguish and highlight that discussions about sex characteristics and gender distinctions are two separate conversations with two mostly unrelated minorites. Very often I see intersex people's existence being used as a conservative gotcha for support of trans folk like myself and... It doesn't work. They know trans and intersex folk aren't the same thing and you are trying to red herring them off of the discussion they really want to have. Also... Intersex issues deserve more individual spotlight where they aren't mashed in with transgender advocacy. They have their own unique battles with beaurcracy, society, mental health and so on. Give em some love sometimes. Talk about how our social concepts of binary sex has medical and social consequences for them. They need the press too.

Severing the old euphemism "gender" completely from the word "sex" so we can better have these discussions is a start. A lot of Conservatives use the two interchangeably to imply that gender doesn't exist, to them it is just a synonym for sex so word combos like "biological gender" is developing into a unique alt right dog whistle with it's own google alt-right web result pit so just wanna give you a heads up on that front.