There are only paperbacks. By "hardcopy", they meant "printed".
I sell print editions through Amazon KDP and IngramSpark. Amazon is the lion's share, so I designed the print edition based on the formats they offer. At the time I started working on it, KDP only supported soft covers. They added hard covers right as I was finishing the book, and I didn't want to have to go back and redo everything.
I have to admit that "Crafting Interpreters" is pushing the limits for what you can get away with on a soft cover. When I first started writing the book, I expected it to be (much) shorter, but I just estimated wrong.
If I had a time machine, I might go back and tell myself to print it as two separate volumes.
I'm not sure how these services work, but are you planning to offer hard covers as well for a "next print"?
I've had my eye on Crafting Interpreters for a bit now, and I don't mind paying extra for a nicer version — especially if it's going into the pockets of an independent writer.
If I do a second edition, I'll probably think about it then. I don't have any plans to touch the book any time soon. I worked on it every single day for six years, so when it was done, I was really ready to be done working on it.
I have hardcopies of both and "Crafting" remains my all-time favorite programming book.
It's delightful, educational, and beautiful.