Plex for books?

I've picked up an eink Android tablet, which is awesome. However I have plenty of ebooks I've purchased over the years on places such as Humble, and I was wondering whether there was a self hosted solution like Plex/Emby/Jellyfin but designed for ebooks.

I've seen Calibre but it doesn't seem to be quite the same thing, and running a sync is a bit clunky for the spouse factor.

Is there anything that would index the books, show a bookshelf and allow me to read them, with offline support?

Preferably with an Android app for reading with, and the reader handling eink rather than scrolling.