Many people have already mentioned Apple's AirTags. We used them for the first time on our last cruise (Constellation). All of our luggage arrived at our stateroom except for one (mushroom symbol). The AirTags allowed us to keep a watchful eye on it.
I was also starting to wonder if this piece of wayward luggage was somehow impounded in the naughty room for having something illegal in it (I wouldn't know what that would be, but it turned out not to be the case).
Fortunately it got delivered to our stateroom well before we sailed out of Rome.