According to Google's specifications, the Google WiFi devices use a 5V USB-C power adapter and consume ~9W (1.8A).
You can use the Konnected WiFi Router Backup Battery to protect your Google WiFi from power outages, but you'll need some additional cables. You would need a USB-C cable to connect the battery's USB port to the Google WiFi. You will also need a 12V 2A power adapter for the input power to the battery, as the power adapter that comes with the Google WiFi is not suitable for charging the battery.
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UL Listed 12V 2A power adapters for keeping the battery charged. The Power adapter that comes with Google Wifi is not suitable for charging the battery.
|USB-C cables connect from the USB port of the battery to the Google WiFi.|