Hmm. I've never considered using a non-DJI battery on my own drone. Something about the possibility of a failing battery on a device flying high up in the air really scares the crap out of me. The real test is not really whether or not the battery works (I'm sure it does), but how long it will last with repeated charges and flights under its belt. The DJI batteries hold up really well. I wonder if this Powerextra 2-pack is just as good for $115 (a normal DJI battery costs $89).
I just got off of a long flight and come home to news that the FAA wants to ban laptops and other lithium-ion battery devices from check-in luggage on international flights.
The Omnicharge Omni 20 is a 20,400mAh portable battery capable of delivering up to 100W via the AC outlet. This is the only external battery that can not only power the 87W MBPs (15-inch) but also charge them during use (an important factory when shooting on location). The only downside here is that you would have to carry the full AC charging unit along with this Omnicharge external battery.
This leaves plenty of room in the market for an external battery that could make use of the high-powered USB-C ports for charging without needing to lug around the Apple AC adapter for the computer. If somebody would put this type of battery out with a high enough capacity, I guarantee you at least a good number of sales in the photo industry alone.