That's a great point; I'll try to add some more of these. I definitely meant to link to the app store page from the docs; I actually just updated them to include that.
It's a full ebook/audiobook library, with sync, though I've focused much more on the reader experience so far than the library management experience. Improving the library management experience is on the horizon, though!
Is it a ebook/a book library like audiobookshelf with sync or just sync? ( https://www.audiobookshelf.org/ )