Just got the email that it is in stock now. Ordered one to put most of my OP w/accessories into one solution.Will put OP, smartphone adapters, Polar Pro ND filters into charging case. Will still need to carry controller wheel separate though.
Looks like about 1.7 additional charges from the case (1500 mAh / 875 mAh), plus a fully charged OP = 2.7. This should equal for 4K about 4 hours (2.7 * 1.5 hours per charge?)

https://store.dji.com/product/osmo-pocket-charging-case

Osmo Pocket Charging Case
USD $129
Shipping:  Free

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Or you could just buy an Anker usb battery and cable and a case for more than half the cost.

It’s pricey, like the fact it gives more than one full charge, can it be charged itself by a battery pack ?

DJI-Osmo-User-1 Posted at 4-4 08:35
Or you could just buy an Anker usb battery and cable and a case for more than half the cost.

Its for convenience and to keep the setup as small as possible ,but if one can carry bag then usb power bank is a better option .Since that can be used while doing timelapses as well.

Pity the selfie stick isn't out, that would be a darn site more useful to many of us than this

Do note that this charging case do not have the same portability as a power bank.

While it does have, as you said, around 1.5 charges of OP have, you cannot charge OP while it is in use. It only charges when you don't use OP. It only makes you not forget and brings an empty-charged OP outside.

Also, this charging case charges using the data port on the OP side. Personally, I'm worry that the data side port will eventually get worn-out. Switching between charging case, phone adapter, and wheel controller (if you buy one).

Stuge234 Posted at 4-4 11:20
Its for convenience and to keep the setup as small as possible ,but if one can carry bag then usb power bank is a better option .Since that can be used while doing timelapses as well.

Problem is that it's not small, Arguably a small powerbank is more compact and you can charge even while you're filming. It was a cool idea but not that practical.