Here's some more girl content off the top of my head while I would ponder an answer, but I would say the main reason more girls aren't into hang gliding... is because...
gliding and primary gliders use to be the primary most accessible stepping stone gateway into getting your feet off the ground and flying... aka 1930's... and again briefly... 1980's...
Not so much any more, there are more accessible ways to get airborne now. Now you don't need to have your butt in a cockpit to enjoy flying, you can do it via a SIM, FPV quadcopters, or RC airplanes. And now, you can't even find a primary glider or hang glider at your local airport or flying club or EAA hanger. Gliding schools are usually hidden away clics or clubs only located near or in mountain ridges and ranges or by coasts.
https://www.youtube.com/@MaiOnHigh/videos
https://www.youtube.com/@FlyingMAir
https://www.youtube.com/@DutchPilotGirl/videos
https://www.youtube.com/@CourtneyTakesFlight/videos
https://www.youtube.com/@therealonigiri/videos
https://www.youtube.com/watch?v=NLsy7SRMPjk
https://www.youtube.com/shorts/zWrLEwtzxoM
https://www.youtube.com/@LittleStellarFox/videos
https://www.youtube.com/@NarineMelkumjan/videos
https://www.youtube.com/@AleeshaFPV/videos
https://www.youtube.com/@TheRcSaylors/videos
I have a joke about the great primary glider bonfire the old Elmer's at EAA had to keep women out of aviation, but in reality EAA never did have much of anything in the way of primary gliders or tow planes to get women and kids interested in aviation, it was always an old boy's club of guy's that pop riveted their own airplanes together with scavenged engines. I don't even think any of the EAA clubs had a single trainer like the one I made a video about (https://www.youtube.com/watch?v=DVvDY_V3EhM). Which is sad, because the few times I've been to our own local EAA monthly meeting micro-democracy in action, there were as many women and kids there as men. And only a few planes in the hanger owned by men tinkerers. I know they fly, they fly their buzzing ultralights over my house in the afternoons sometimes and I'm 13 miles away.
https://www.youtube.com/@BernardsHistory/videos
My Crazy friend Greg in Tempe, Arizona did nothing for years but build Primary Gliders and Bargain Basement ultralights... from plans.. the guy has insane building energy... yet had never covered or flown one. I suspect he has no friends to tow him aloft even if he did. I introduced him into FPV quadcopters a few years ago, and he's been zooming around his local neighborhood ever since happy as a lark, sitting on the ground in his front yard wearing ungainly ghetto setup of FPV goggles and controller he's hodge podged modified together. He doesn't even have a computer, he's managed to configure it all with his smart phone... which blows my mind at the tenacity he had to get airborne hell or highwater.
Computer SIMulator setups, Primary Gliders, and Rogollo hang gliders - why aren't they at every EAA club? Lack of funds, or lack of interest? Probably both. You would think every 3rd or 5th EAA club should at least have a TOW plane. (Spot the Volmer Jensen 11 Chanute style box kite biplane tail in there) https://www.youtube.com/watch?v=imAKYa_pzw8
I've seen Menonite chickas in their doiley hats and dresses at air shows... Menonite (think Amish) chickas of all things... take one of those on a discovery flight, that would be a hoot. They rarely get out of the house only to go grocery shopping or to church and are sick I'm sure of poetry class.