The two are not related in any way but name. Google shut down Sidewalk Labs many months ago. Now, Amazon launches a new product called Sidewalk that allows for some sharing of long range low bandwidth Bluetooth over private WiFi networks. It extends the range of both your devices as well as your neighbour’s devices.
And it’s not crazy.
But it does require putting some trust in Amazon, which might be a bit of a stretch except for those who already buy into the Amazon ecosystem (e.g. millions of US households).
At some point, such a project might extend into Amazon Eero routers. Google will like follow suit on its own hardware like Google WiFi.
Where does this leave ISPs? They are going to be squeezed out by sharing of bandwidth and further by the launch of satellite based services.
Welcome to the Wild West again.