it’s a bit different, in that they’re just constantly broadcasting a singular id, over and over. The “tracking” is the application on various devices which receive the broadcast and report it to Apple, along with that device’s location.

Sidewalk was packing up actual user data and running it over your network, which has other implications.

Edit: ise if you have an airtag in the middle of nowhere, and there’re no apple devices around to receive the broadcast, there’s no way to track the tag. They work well in cities just because of the sheer density of iDevices out there.