"Your purchase could not be completed."
Purchasing ebooks for myself via Apple Books works just fine, so there's no problem with my payment method, but when I try to purchase an ebook as a gift, I get this annoying message.
So I went to Amazon and bought the gifts as Kindle books. As an Apple stockholder, I don't like to see Apple lose a sale to Amazon through sheer inattention.
iPad mini 6, iPadOS 17