Let me tell you about my covid experience in Italy. I was not on a cruise, but on a land vacation when I got Covid in August. Tour company had me do an "official" test with the Italian Authorities. My passport was supposedly flagged. I was never contacted by the Italian Health Authorities, and just quarantined in the Venice hotel I was already staying in. I was booked there for 7 days. The night before my booked flight home, I did my own self test with a test I brought from home, and it was negative. I decided to take my chances, and went to the airport to see if they would allow me to fly. Checked in, passport checked, and... not a word about my covid diagnosis. I flew home. Easy. Now, if I was still testing positive, I wouldn't have tried this. This is just my personal experience, so it may not work this way for someone else. Best of luck with your situation.