From my experience as a bookseller I know that most people want to read more, but the full context switch to "reading" is increasingly difficult for many. I could be biased, but I've always found email to be underappreciated as an app platform.
With Driplit I wanted to use email as a way to fit books naturally into my day. Driplit allows you to read books over email, one ~500-word "drip" at a time. We have about 1500 public domain books at the moment. I recently allowed uploading private EPUBs too.
I'd love to hear what you think.
ps - https://alivreouvert.net/2015/03/19/une-bibliotheque-peut-el...
The "read instead" photo is my old bookshop Lorem Ipsum Books. The blog is not mine.
There's also an option to send multiple times a day.