I’ve read reviews to similar panels. The closest I’ve seen is one called BigBlue. Same wattage. On one review they was able to get 2amps of charge on one port. It’s using Sunpower cells too. I’m hoping that this BlitzWolf will deliver the same performance.
Here is a video review showing that.
I think he’s able to achieve 2.1A using a load tester. I am thinking the charging circuitry for the panel will only deliver more current to a device if the device requests it.
What charge rate does your 18650 charger output? 500mA or 1000mA? Also what is the charge input /charge rate for your battery bank? 500mA? If both devices only request 500mA each then your results are pretty close for both devices to 1000mA. It won’t matter how much brighter the sun exposure is if it is charge limited.