I'm surprised it does not have a sensor of some sort to at least test the charge level of each pack.
As far as I know, there is no real way to know the actual (vs. estimated) state of energy storage without exercising the battery. This is why at best what we see on screen is an estimation by the BMS. We can count the energy going into, and out of the battery, and we can even measure the delivery and storage efficiency, but all of this requires moving electrons. Perhaps someday we'll be able to scan a device and know its true state of charge.
I found this resource online, if you'd like to dig in a bit deeper on how state of charge is measured (From Battery University):
Measuring State-of-charge - Battery University