A family member works for a large chain of car dealerships. They regularly buy vehicles at auction. It's not uncommon that they find trackers on the vehicles. Here's a picture of one he sent me to play with a couple years ago.

The battery pack on the left, and the tracker on the right were in a magnetic Pelican case attached to the underside of a black Escalade. The sim in the tracker was from some US MVNO that I didn't recognize.

https://i.imgur.com/VLzTPt4.jpg