Tech side: according to https://aws.amazon.com/iot-core/features/ the physical network seems to be implemented using LoRa https://en.wikipedia.org/wiki/LoRa which has a range of up to 10 km in perfect situations (so more likely 1 km in urban environments)

Edit: actually maybe Amazon uses a proprietary version of LoRa: https://enterpriseiotinsights.com/20201208/channels/news/lor...