From my experience, Amazon is quite strict about publishing low-content and interactive books such as coloring books, puzzle books, and blank journals as Kindle eBooks. These types of books are mainly designed for physical interaction, such as coloring, solving puzzles, or writing, so they are generally better suited to paperback or hardcover formats. I actually tried converting one of my coloring books into a Kindle edition last year, but Amazon did not allow it. That experience made it clear to me that these books are still much more suitable for print. However, I’m hopeful this could change in the future. As e-reader technology continues to improve, it would be interesting to see Kindle support more interactive formats such as coloring, puzzles, and other activity books. I think there could be a lot of potential there.