I have a Watchy, a kit "smartwatch" built around an ESP32, that now runs firmware that listens for Axon/Taser and Flock bluetooth and wifi prefixes, and vibrates on my wrist when it detects them.
Also, 10 or 15 years back, I wrote an Android app to do ALPR on the live camera view with the phone in a holder that let it see out he windscreen. I collected licence plates by spending an hour or so every few days over a few weeks sitting at cafes that had a good view of the marked and unmarked cars arriving and leaving the three major police stations nearby. It did work, but the camera in the Galaxy S3 and S4s I had to try it on couldn't get images good enough for OCR until the cop car was so close it wasn't useful... I contemplated experimenting with a drone camera gimbal when I was building and flying camera drones around 2014/2015, possibly using one of those clip on telephoto lens's that were common back then - but by then I'd ditched the car and I didn't figure I;d be able to build that to work on any of my motorcycles.
Also, 10 or 15 years back, I wrote an Android app to do ALPR on the live camera view with the phone in a holder that let it see out he windscreen. I collected licence plates by spending an hour or so every few days over a few weeks sitting at cafes that had a good view of the marked and unmarked cars arriving and leaving the three major police stations nearby. It did work, but the camera in the Galaxy S3 and S4s I had to try it on couldn't get images good enough for OCR until the cop car was so close it wasn't useful... I contemplated experimenting with a drone camera gimbal when I was building and flying camera drones around 2014/2015, possibly using one of those clip on telephoto lens's that were common back then - but by then I'd ditched the car and I didn't figure I;d be able to build that to work on any of my motorcycles.