When you’re talking about gay folk and same sex attraction conceptually, you don’t call it “homosexualism” or “gayology”. You would use the term homosexuality or same sex attraction.

Okay, so if I want a single word, "transgenderality"? That really just sounds bizarre, I have to say. Not to mention I've never seen any person talking about trans issues ever say/write that.

The issue is explicitly the “ism”. The -ism suffix is used to denote political and ideological beliefs

That's only one way that suffix is used, and it's assumption on your part that when you see that suffix, that that's the way it's being used. In other words, I think you should allow for the possibility that it ain't that deep. Was it not obvious from the context of what/how I was writing that I wasn't coming from a transphobic place?

-ism is used for all sorts of nouns that simply describe a state of being (e.g. autism, alcoholism, absenteeism), and that's all I aimed for. And from what you said in your comment, it seems like this is uncharted territory, if there's no actual single word term regularly employed for this particular state of being—all of your examples are multiple words.

P.S. By the way, I'm not at all dissuaded by something that is inherently benign being popular among shitty people—in my opinion, all the more reason to take it away from them, by using it benignly more often than they use it pejoratively. It was successfully done with "queer", I say keep that train running!