Why is the deg needed in this sentence? Is ønsker a reflexive verb? Does the sentence make any sense without it?
The reflexivity emphasizes that it's a wish for oneself. It can be dropped, but that sounds archaic.
I think the sentence can be better translated as "What do you wish for yourself?"
What are wishing for? Det høres ikke riktig på engelsk etter oversettelsen
I agree, the sentence "What do you wish?" sounds awkward in English in this context, it should be "What do you wish for?", in order to imply the wish is for oneself.
"What do you wish" sounds rather like what a Genie might say after being released from the magic lamp
I agree entirely with Scotty.