Curious about these builds.

[BeOne]

Hi phtumshk. No a P channel works similar to an N channel but opposite. With an N channel you apply a positive voltage greater than Vds(th) to the gate to turn them on and with a P channel you apply a (in simple terms) 0V to the gate to turn them on. To ensure it turns off you tie the source to the gate with a resistor so when the button is released the gate returns to source voltage.

So, what's the benefit of a non regulated mod if the vape does decrease slightly during the day? Why not put in a simple LDO voltage regulator so the vape remains constant especially with parallel mods? Probably don't have enough voltage overhead for the series version unless using a slightly more complicated buck/boost regulator.