So, you *CAN* charge via POGO connection and use an OTG device at the same time.
To make it happen, you need:
- A POGO power cable
- An OTG Y-cable with power (This is important! A regular OTG cable will not work. It has to be a Y-cable.)
- Two USB power sources (e.g. two power adapters).
Plug all of that in. The OTG Y-cable will supply power to your USB device. The POGO pins will power your Nexus. Your battery charge will gradually increase as you use it.
Tested with a Nexus 10 at full brightness, running an app that disabled sleep, and with wifi off. With a 2A charger, it gains about 4% battery power per hour.