I would like to know it there is or will be any external battery charger for the ronin SC like there is for the S.
I shoot weddings, and one battery grip would not be enough most probably. I'd like to know If there is any possibility to charge a 2nd battery while the gimbal is in use with an other grip.
Also I'd like to know if the SC can power a camera via the provided USB port under the quick release plate. I have sony a6500 and a6400. Will I be able to charge them with the gimbal while using?
Thanks for your answers in advance.

If the battery grip contains built-in 18650 lithium battery, you cannot disassemble the battery, maybe you can prepare a power bank or the external charger with power bank function (such as Xtar PB2S http://www.xtar.cc/product/XTAR-PB2S-Charger-122.html). If not, then you can charge it with the common battery charger. For all the device, if you use them while charging, the temperature of the device will rise quickly, which is not safe and damage the device and battery.

As always with things like this, it would be awesome to have official options.

It would be really nice if DJI would release an official charger just like the Ronin S has. (https://store.dji.com/product/ronin-s-battery-adapter)

Agreed.  Seems like a design miss to have to charge batteries only through the gimbal. Having a separate charger (like many other DJI products) would make the kit more useful.