I wrote a blog post on generalizing segment trees: https://sharmaeklavya2.github.io/blog/generalizing-segment-trees.html

It's about a method of generalizing segment trees by expressing query outputs as monoids and update functions as composable endomorphisms. The blog post explains what these terms mean, why they are suitable abstractions and demonstrates concepts with examples.

Can I please get comments/reviews/opinions on it? Do you think it is (or can be slightly altered to make it) useful for others?

You can see the templated C++ code here: https://gist.github.com/sharmaeklavya2/99ed35efbb639bbe7d7b46b89b74fea0

The blog post turned out to be more detailed and theoretical than I was expecting. It's more concerned with mathematical and algorithmic aspects than the practicality of using it in contests. But I can change that if you think that would make it better.