Why are there so few resources for learning how to build plugins?

There’s so much information for the basic stuff, but so little for this? I frequently see the plugin course at copilot referenced, but like with so many of their products and services, I find it rushed and confusing. Is there a good alternative that I’ve missed? I really need some help figuring this out.

I don’t think there’s another good ressource for learning this. I started with this and this help me a lot, but you need to know JS enough. Don’t hesitate to post question here and some user can help you.