It wouldn't be a very smart move for Napoli to sign Ronaldo I think.

Because there is no need for spending a lot of money for Ronaldo's salary for Napoli. They must already be contented with their current strikers and especially Osimhen of course. I don't think that there is any meaning in spending that much money for a player who will be likely to be in the subs mostly. It wouldn't be easy for Ronaldo to have much chance in the starting eleven of important games. But maybe it is already enough for Ronaldo to be a part of the team just because they are in the Champions League.