It would be great to be able to have an ebook store but that sounds like it would involve a very complicated licensing situation.
I was thinking instead that I could have deals with sites like royal road (or directly with authors on the site) which feels like it would be easier since the average author on those sites would probably be more willing to deal with a random person like me. What do you all think?
I have a similar issue - it requires people to download and try a browser extension, and I have trouble explaining how it works to a non-technical audience. The terminology that lets me succinctly explain it on HN doesn't work so well in other places.
I've found that most of my paying users have come from the overlap of technical people and language learners - most came from a single HN comment that I made before logging off for the night!
It doesn't scale well though. My marketing has been largely unsuccessful.
Your suggestions sound like a good plan, if you can convince them to deal with them. You might find that difficult because of the chicken and egg problem: They want users in order to make it worth their time dealing with you; you need them in order to get users.
Perhaps you could make it work on PDFs? Those tend to be easier to find than epubs.