If you're looking for a platform, I STRONGLY encourage you to look at either OpenDSA or Runestone, two open source interactive textbook platforms. I've been hacking on the latter this summer, porting it over to Runestone for a course I'm teaching (on Computational Thinking) (https://github.com/RealTimeWeb/runestone-flask is my public facing copy to give you an idea, but it's not a full copy of my port).
I'm very familiar with the development teams for both these platforms, and they're both very friendly and desirous of collaborations!
I'm very familiar with the development teams for both these platforms, and they're both very friendly and desirous of collaborations!