The thing is, this wouldn’t even be so hard to write. I’ve been doing some hobby work with BLE and I’m continually surprised how easy it is to basically sniff and in many cases interact with any several dozen BLE devices around me in my condo building. Things like smart TVs, headphones, and any other number of random peripherals.
All these tracker thingies use BLE and will broadcast out frequently so they can be discovered. Basically you’d need some code to use the GPS to track your location and alert you when an unexpected BLE thingy is traveling with you. I’m guessing this is basically how the AirTag alert works here - they just filter it to their own devices.
