This reminds me of an app I wrote a few years ago when learning R: https://mzgw.shinyapps.io/book-recommendation/
My friend needed a way to determine the Flesch-Kincaid readability score for a selected paragraph, and was using Microsoft Word for that. I wrote a script to automatically parse the scores for all txt files provided, then started to wonder how different books fared in that aspect, how readability scores map to language proficiency levels, and what can be told about the book in general using simple analysis tools. It was a fun project but the readability scores were far from expected — eg I hate Joseph Conrad’s Heart of Darkness and always find it frustrating to read but the readability score is actually not that low.