Well to be fully clear, I see if Anker can make a 5000mah 10W input 10W output portable charger, they made in a flat shape in the Slim 5000 and in the cylindrical 5000, then they should be able to make a 10000mah 20W input 20W output portable charger.
They then can take the 10W input in a few different flavors. One flavour could be dual 2A input, another could be say a single USB-C input. One flavor of output could be dual 2A output, another could be one USB-C output.
What Anker chose to do is a bias to QC in the Powercore II 10000. That ignores the entire Apple owner community and most Android users. QC is a 18W upper standard, so other similar Wattage in other than QC should be next.
I meter and feel the temperature of different portable chargers, I do find the cylindrical shape tallies with laws of physics you'd expect that a cylinder is inherently hotter (cylinder = smaller surface area per unit volume) than a flatter shape. So given that I expect something the shape of the Powercore II 10000 can be made in other flavors.
I meter devices through their charge cycle. For about half their charging time they take less than the maximum. Hence in a single-port portable charger, half the time it is not working at its full capability. To get more out of the portable charger, a dual socket 2A output will on average not be all ports taking the max. Hence they should be able to offer say 20W budget total, each port rated upto say 3A then if I plug in say a 3A tablet and a 1.3A phone, then they'd not be at full charge initially but the phone would drop its ingest at 85% and then the tablet gets full 3A. Also if you use a device, even if you just touch the screen, then the metered ingest drops as the device responds to thermal pressure. So, again, if you plug in a portable charger to a device you are using, there is opportunity to charge other devices which are not being used on the other port(s).
i also see the Li Poly products seem (anecdotally) out of stock more easily, that is telling that Anker has a supply probiem with Li Poly. That is causing prioritization of product releases. I hope the bias to QC is addressed soon.