I have 3 different libraries, one for comics, one for TTRPG books, and my main one for actual eBooks. My main library is over 4GB with over 1,000 books.

No, I haven't read all of them, but I am working on it. They have been collected over the last 15 years from Sony eReader store, Kobo books, Amazon Kindle, B&N, Archive.org and other Public Domain books hosts, Humble Bundle, Story Bundle, and various other places.

Largest categories are Sci-Fi, Fantasy, and Mystery.

I wish there was a way to link to an Android app.