I've been building a little app on the side that allows me to primarily read my books in epub, mobi or pdf -> text format but generate readouts on demand for only the bits I want (highlight, paragraph, page, chapter) so that I can continue while I'm on the go, without having to bifurcate between apps - this might already exist but I made mine
Naturally, I also added the ability to highlight, leave notes and ... ask questions (via API)
Even with incredible models, it's a decent amount of work to get this to work nicely