Epilogue is a new entry in the micro.blog suite of apps, currently in beta, that can be used to manage your micro.blog book shelves. You can also write blog posts to your site from within the app. I am not sure a separate app is the way to go here, but I think I will find it useful all the same. Shortcut support (or share sheet support) to provide some integration between the Kindle app and Epilogue would be great. Since bookshelves are lists, export to OPML format would also be great. I managed my 2020 reading list in Little Outliner and I like the end of year result.