The newer USB-PD allows a fully flexible choice of current and ampage, the device and the charger negotiate, so you can do anything you want, it is really only limited by the heat of recharge, so Anker can build a prototype and measure it. Indeed, they could have a thermo regulator so that in say a cold location the recharge is faster. That regulator would increase cost, so a cheaper way is to measure it in the lab in a warm location and fix a safe upper limit.
A 3400mAh 4V 18650 has a safe standalone (able to cool itself with no other cells around it) at 12W input and 24W output. 8 such cells have thus 96W input and 192W output, these both reduced by the cells being packed together warming each other up. Only Anker would be able to prototype and measure and decide. Yes, 45W is perfectly possible, but its the heat. A metal jacket to dissipate heat, with a thermal compound inside would help. Metal is more expensive, thermal compound is an added cost. You willing to pay >$100 for a faster Powercore? I’m not!
With a more efficient IQ2 the other cause of heat from the DC-DC should be reduced, as well as the cost.
BTW IQ2 and USB-PD are perfectly possibly the same thing, as USB-PD is superior to QC3 and also why QC4 and essentially the same as USB-PD. So we have the cables USB 3.1, we have more efficient electronics, we have the fully flexible negotiations, all we need is the will from Anker to make it, followed by the will of the consumer to buy it.
What is the iphone 10 max recharge and what is it charging technology exactly?