OK I haven't even gotten my first iOS device yet--the Mini is on the way--but Kybook 3 looks like my app. I read the description on the App Store page, and they had me at....
• Draw annotations in any ebook (Apple Pencil support and just by touching).
• Annotations exports in Markdown, HTML, PDF, RTF formats.
Wow, why don't we have a reader app like this in Android?