As Zmrzlina explained in another comment here, to shop is generally shoppa in Swedish. So it shouldn't really be accepted anywhere, but it might have been added in some places anyway. I don't think it hurts so we're not going to weed it out but on the other hand don't expect us to add it everywhere either.
To me, saying "I am buying books" and "I am shopping for books" are similar enough for me to think of them as synonymous.
On the other hand, I suppose since the heart system is dead and gone [at least, I think it is; I only Duo on my phone these days], it no longer feels as bad to be marked wrong for something. If you're technically correct, but still marked wrong in order to teach the lesson, that's probably better in the long run.