With the purchase of a PocketBook InkPad Color 3, a good cover was a must. The Coolblue website offered three (at the time): a green one (not exactly my color preference), a black one, and a blue one. After some searching on the Pocketbook website (the cover was supposed to be from PocketBook, but there's no indication of that on their website), I had a quick chat (with an AI: if it says PocketBook, it must be from PocketBook...), but without a satisfactory answer.
It turns out it is indeed from PocketBook, fits very well, is sturdy, so a good choice. The fact that the Origami can stand the reader upright wasn't entirely clear to me in the description at first, but it's a nice bonus.
Now I just have to wait and see how long the cover will last. The cover on my phone(s) usually wears out before I'm ready to write it off...