Ok, I get what you're thinking but there's more to it than that. Resistance and voltage are the two factors related to current draw in both mechs and apvs. Look at the chart below to see the relationships. As atroph stated in his post voltage, res and current are real.....wattage is calculated. This is true for the mod but not the for coil. The mod provides voltage to the coil and the coil draws current from the mod based on that voltage and coil res. Wattage, in the form of heat is produced by the coil, not the mod. So wattage is real too in that sense.
So, if you get a handle on the ohms law formulas for mech mods it should become readily apparent to you that when you set a wattage value on your apv you are actually setting voltage; even though your apv is displaying the change in watts.
View attachment 480399
So, in the end, your apv doesn't actually measure wattage or current draw even though it may display them. It only measures voltage.....even the res of your coil is a voltage measurement (voltage drop across a shunt resistor in the mod).
Of course it has been 30yrs since my formal electronics training, much has been developed in electronics since, but I'm pretty sure electrons still scurry around the same as back then.