Bags are an excellent use case. There's a few travel bags that have motion alarms on them already. You can set the bag to make a noise if it's moved before you unlock it with your phone. I will absolutely put these in my bags—partially because ill be able to tell how far away they are on the baggage conveyor.
But depending on the distance they can go from you before you have it alert you it can be a great suitcase-is-being-stolen notifier, and a way for the police to find your stolen items.
I do a lot of work in the camera business around journalists and we often all have the same model cameras. I put electrical tape on my gear now to tell it apart, I'm definitely going to attach an AirTag to my camera strap and in my bag.