Yes I like the Idea of the lipo battery pack with charging. Not sure if you need to add other parts, they can be stacked. Maybe also a version that includes solar powered changing.
Bat pHat
Sun pHat (Solar charging hat) (see what I did there)
Blue pHat (Bluetooth LE with the nRF51822)
ESP 32 pHat (when ESP 32 available) They already have the ESP8266