I tried using Garmin's rear view radar for bicycles 'Varia R TL515' that can detect the approach of a car with a millimeter wave radar and can also be a tail light -
Tutorial - Edge Series: Pair Varia UT800 and RTL510 - YouTube
Garmin Varia RTL515 Rear Light And Radar, Black | Bikeinn
Garmin Garmin Varia RTL515 Bike Radar and Tail Light - Cam2 Trail Running & Outdoor Gear Store
Varia Rearview Radar RTL510/RTL511 - Suggerimenti per l'installazione del dispositivo
Varia™ RTL510 | Discontinued | Garmin Hong Kong
Varia Rearview Radar RTL510/RTL511 - Installazione della staffa universale
Garmin Varia RTL510 Rearview Radar Tail Light - Black for sale online | eBay
Garmin Varia RTL515 Cycling Rearview Radar and Tail Light with Bike Phone Mount Bundle - Walmart.com
Manuale Garmin Varia RTL510 (Italiano - 12 pagine)
Customizing The Radar Alert Settings With Your Edge 1030; The /Rtl516 And The Varia App; Pairing The Varia Radar Device With Your Smartphone; Viewing Radar On The Varia App - Garmin Varia
Garmin Varia™ RTL510 | Bike Radar | Rearview Tail Light
Garmin Varia RCT715 review – Radar tail light adds a camera | T3
GARMIN RTL510/RTL511 Varia Bike Rear Light with Radar Owner's Manual
Varia Rearview Radar RTL 510 [Discontinued] - TTOT Limited
Garmin Varia RCT715 Rear Radar Camera Rear Light | Bikebug
Garmin Varia Review - For me it's a game-changer - YouTube