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 elements of a monoid 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 or interesting?

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.