Series sub folder inside a collection
Many authors have a series of book about a certain character. I want to create a folder for the series inside an author’s collection I have setup.
Not even just this. You should just be able to create multiple levels of collections for whatever you want. It can't be that hard to program, and if Apple Books wants to keep up with technology that already allows this type of thing (Kindle, Calibre) it really needs to become much more user-friendly and customizable.