I too use the AirTags on everything. While not a true GPS tracker, anyone with a phone in range reports the location to the owner unwittingly. But, criminals now search for these tags first thing, so you’ll need to hide them and they can’t transmit outside from inside an aluminum case (same as GPS). I know people who use 2/3 to give the thief a decoy.
At the moment in the US, one can’t pack a battery in carryon. AirTags seem to get a pass but this rule killed smart luggage tags with gps trackers built in from the factory