Besides its interpretation, what did Nebuchadnezzar demand his wise men tell him?

Answer: The dream itself

The king said that if they did not tell him both the dream and its interpretation, they would be cut into pieces.

“The king replied to the astrologers, “My word is final: If you do not tell me the dream and its interpretation, you will be cut into pieces and your houses will be reduced to rubble.”— Daniel 2:5 (BSB)