there are many teams that are playing much better. All the same Real, Manchester City, Bayern, and of course this season's sensation Napoli.
if Napoli manages to maintain their performance and also play well in every game it looks like they can win the champions league this season, of course if that happens, I think this will be history for Napoli and also Napoli can represent a club from Italy to become champions league champion this season , but keep in mind that there are several clubs that have to be beaten by Napoli, namely Manchester City, PSG, Munich and Real Madrid because they are the 4 big clubs that I think are scary this season.
Even if they are able to maintain their current form but as you said the team they have to beat is a giant team, especially if they meet in the round of 16 it will be very difficult for them to beat them. The Champions League is not like Serie A and the competition here is much more competitive and the teams here are much stronger than you can imagine. I still doubt them in terms of mentality, because here it will be very influential for their game against a much stronger team.