“Also I’ve started a Friendica manual at https://help.friendica.onl/ but it needs to get content.”
Maybe you may translate some content from this guide: https://friendica-hilfe.gitbook.io/friendica-hilfe ?
Most of the functions should be instance-independent (although loma.ml has activated many add-ons)
Open Library is the main data source for Bookwyrm for book data. Bookwyrm is an application in the Fediverse that can be used to find and write reviews of books. I wouldn’t see that as a contradiction.