When I was tested for illness on the Constellation in January, the results included Flu A, Flu B and RSV as well as Covid 19. That allows the cruise medical staff to handle appropriately.
We do travel with only 22" roller board bags and do keep them with us. What you need to consider is if it will fit in an airport sized security scanner. We board, drop our bags in our room, put valuables in the safe and get out and explore.