The source site/paper won't load for me at this time, but if the device has a cellular modem in it for network connectivity, it will 100% be assigned an IPv4 address from the carrier. Unless this device is using an APN at the carrier level, or is using a SIM provider that provides some additional security.
Yes. I was looking for this comment before saying the same. This is the biggest selling point of Sidewalk to appliance/product companies. All the usage data, ad data, analytics, even remote control of devices can now happen even if your devices are completely disconnected from your home WiFi. If your neighbor has an Amazon Echo... now its basically connected to the internet. Even if you don't have neighbors, there could be a LoRa gateway a mile away on a cell tower, and its now connected.