During Klopp's era at Liverpool, I really haven't heard that they are disappointed with the players they bought. Nunez is a good player and I think Klopp got interested in him when he scored against Liverpool in a Champions League game a while back. He may not be on par with Mbappe, their level is different but they are players with good finishing.
Klopp knows that with the potential of a Nunez, he will definitely provide an even better breakthrough for a Liverpool squad that needs attack power. No wonder when Klopp targeted Nunez to be able to adapt to other players. I think Klopp has been watching Nunez for a long time and when the transfer market opened quickly Liverpool took Nunez before other clubs took him.