Suggestions for sites to add:
https://www.deviantart.com - An English art site with a category for literature. Supports cover images and embedded images. Doesn't support chapters.
https://www.pixiv.net/novel/ - A Japanese art site with big section for fiction, currently hosts 10,000,000+ stories in total. There are browser add-on converters for it to txt, but nothing for epub. The editor supports embedding art from the site, and furigana/ruby (smaller text over text). Supports covers. R-18 stories require login.
Search example:
https://www.pixiv.net/novel/search.p...g&word=english
Thanks a ton for this plugin, it's incredibly useful.