At first glance, I thought that this was just an automotive power inverter (it isn't) or some kind of weird jumper system (also not it). When I looked closer, I saw that it was a large battery pack with an onboard power inverter for wall plugs and a USB-C port. Unfortunately, and this is my biggest gripe with all battery packs in general, not just this one; there was basically no useful information on the packaging to determine what the output ratings were.
My use case; reserve power for a 15" 2017 MacBook Pro, charger for an iPhone, an iPad, and a Nintendo Switch, battery powered wall plug for special tools or other equipment.
On the first, there are two ways to charge a 2016 or 2017 MacBook Pro from this. First is the onboard USB-C port, second is the inverter to wall power. From System Profiler, I was able to see that the USB-C port on the myCharge provides 15 watts of power; enough to trickle charge a MacBook Pro or decently charge a 12" MacBook. For some reason, the USB-C port being a 15 watt port is mentioned nowhere on the packaging or online. So, now you know, it's a 15 watt USB-C port. 15W over USB-C. This does not have USB-C power delivery.
As for the wall plug, it powers the 87W Apple USB-C brick and the MacBook Pro recognizes it and shows 86 watts of available power. Good job! Does exactly what it says on the tin in that regard. If you need to charge your MacBook or MacBook Pro quickly, use the wall plug. The inversion will give you less power due to heat dissipation than trickle charging from the USB-C port, but it will also charge much, much faster. Full speed, in fact. That's the upside of having an onboard inverter.
15W is more than sufficient for charging a Nintendo Switch while playing it; I've gotten away with a 12W iPad block and still gained charge while playing Breath of the Wild; the Switch is impressively power efficient. Standard USB ports, standard iPhone and iPad charging, nothing to see here, move along. If it doesn't charge your phone or tablet then either your cable or you are the problem, not the charger.
The design is great; super solid, nice black matte finish, wouldn't hesitate to take this onto a job site or camping. The charging block for the myCharge is hefty and proprietary, rather than USB-C like many other batteries, but that's the tradeoff for getting such huge capacity and decent charging speed.
In short; an excellent product. I'm knocking the one star because honestly I wouldn't even be writing this review if the manufacturer had actually put useful labels and information on the packaging and I didn't have to conduct power rating testing myself.