Books App does not show the number of books, nor the size?
In my Books App I cannot see the size of my library, items and Mb of each book
Nor is it possible to see the folder where the books are stored?
MacBook Air (M3, 2024)
That's just the way the app is I'm afraid. The podcasts app is the same. It makes it a real pain if you want to synch books or podcasts with an iPod but Apple has decided that we don't need this information. I've submitted feedback the limitations of both apps every update but the Books and Podcasts apps just get worse and worse. There might be better Apps out there - maybe someone will come along with a suggestion.
The books are stored in the users/<your name>/Library/Group Containers folder but that won't be much use to you, I'm afraid.
Send them feedback if you like.