When I was growing up, a lot of queer kids loved HP. There is a literal potion in the books that completely changes you to another person, including sex. I know a lot of millenial trans people who were able to come out referencing that potion and scene and how they could relate or wish they had that potion.
Imo, the books aren't that good. For elementary and middle schoolers, sure, but I don't think JK Rowling is a good author or world builder. I believe the IP/franchise relied heavily on the audience and Rowling backstabbed her queer fans. The same goes for the new game. It's more open world drivel and I think the only way it got this big is because idiots kept talking about it.
With all of that said, having a community on lemmy that is about Harry Potter, and they are clearly pro-trans/queer, leftists/progressives, and ban any alt-right shitters then that is very good and powerful. It's so powerful to get more HP fans in more leftist spaces so they can incept those ideas.
That's reddit. They don't want their users to bleed and the mods that are left are scabs. It will be similar with other sites and it can feel like spam. The best thing you can do is populate the lemmy with HP info and hope it kicks off one day