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.
I have around 7,750 books in mine at the moment. A significant chunk of this was a collection of sf and classic novels that a friend gave to me about 12 years back - boosted by a couple of smaller collections later.
I also have around 2,000 physical books and am slowly thinning those our by adding ebook versions to Calibre.
As for an Android app, I use “Calibre Library” with mine - usually downloading through that and reading in ReadEra.
Do you have a link for Calibre Library for android? When I searched I didn’t find it.
Just curious, did you find the link?