I’ve been working on an ePub reader that saves your book annotations directly in markdown files. If you specify the output directory to be a subdirectory of your Obsidian vault, you can use Obsidian to view and edit the annotations without doing a manual export. Changes made in Obsidian get synced back automatically and deeplinks in the markdown allow you to jump back to the original location in the book in the app.
I’d love feedback and feature requests! You can find the app at https://valla.app and here’s a quick demo:
(If you’ve ever tried to open ePub files on your computer, you’ve probably discovered how terrible most reader apps are. I’m trying to make an app that’s fast, keyboard-driven, supports deep reading, and most of all is local-first and integrates well with other knowledge management tools.)