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.
Of course Napoli are doing a big gamble if they do the signing of Ronaldo in the January transfers because with the existing squad they have been able to look quite impressive so far. In addition, Khvicha Kvaratskhelia is getting sharper with Osimhen up front, which has proven that they are able to make the opponent's defense difficult when facing them. Besides that, I don't think there will be too much hype for a team if they are able to sign him because of the age factor Ronaldo probably won't be playing for long because age will affect his performance. Therefore, I think the rumors of Napoli interest in Ronaldo are only exaggerated by the media.