We had the same concerns when we first resumed cruising Oct 2021 and have done 5 cruises now and remained 100% free from SARS-Cov2 infection.
Here are what we did:
(1) N95 mask everywhere all the time except during eating/drinking
(2) Use outdoor sitting whenever possible, on Panorama that means Lido buffet you can find outdoor sitting, same with the BBQ place, the Mexican and the burger place.. No outdoor sitting for the Italian and Asian restaurants.
For dinner, the MDR doesn't have outdoor sitting. So we risked it, but always asked to sit away from other cruisers and always wear the N95 whenever we are waiting for the order or talking to the waiters. Only took them off when eating
(3) Wear N95 (not the KN95, which usually doesn't have a good seal) when seeing the shows and in Casinos.
(4) Always booked a balcony room with the door opened even when we were sleeping at night
(5) Brought a personal HEPA filter to put on the dining table when in the MDR with mask off
With those protocols, we have avoided infection with the SARS-CoV2 even with 5 cruises so far since the restart in 2021. But that was before the mask mandate was removed earlier this year.
After the mandate was removed, we cancelled the remaining bookings for the rest of this year, I'm not going to risk my life since now it's everyone for him/herself situation without any regard for others. I'm simply waiting for the crowd to be thinned by the virus and I'm pretty sure when 50% of the population is either dead or permanently disabled by the virus after repeated infections, they will probably re-introduce the measures to make cruising safer again and that's when I'll start booking again, hopefully with much lower rate š