Battery Fuel Gauge and Power Monitor (for over current)

the document NVIDIA Jetson AGX Xavier Series Battery and Charger Design Guidelines talks about a sensor to measure the charge left on the battery and, eventually, overcurrent events. These sensors are named Fuel Gauge and Power monitor in the above documentation.

Are these sensors included in the carrier board that comes with the dev kit? If so, where they are?

No, they are not on carrier board. They are just recommended examples to let customer has better understanding on the charger design. Customer should get some from market accordingly.