As it stands charging is very slow, I hope this can be optimized in due course
Charging should work fine. As long as the unit it running, it can be pretty slow, sure, as the unit itself needs a bit of power.
Using a proper power supply (3A, 5.3V) with a good MicroUSB-Cable (not too long and not too thin), connecting this to the USB-OTG port and then powering off the Pyra will quickly charge it.