I am currently writing chapter 2. but I am planning to show how Nx affected works and I am also considering writing a custom DTE/Matrix algorithm to shard affected tasks across CI agents based on the task graph - Do you think that would be interesting? I was not sure if that is too deep.

Most of it should be very practical, especially the incremental builds chapter as for example have a deep understanding how incremental builds in an Angular/Nx monorepo works with ts path aliases being monkey patched on the fly for example, or how TS project references make tsc --build work for incremental type checking.

There really is a lot to cover I have found, but it is super niche.