Bypass, bypasses the regulator = battery voltage output.
On some lesser quality power
devices it also means bypassing some or all of the protection circuitry.
You'd have to look fairly hard to find a newer
decent regulated power device that still uses PWM to either buck or boost output.
For several years DC to DC converters replaced the need for any PWM to control output power.
Meaning most
decent VW power devices made in the last few years don't use PWM, there is no pulsing.
There might be a very slight voltage variance going to the delivery device to provide the exact wattage set due to slight variances in resistance while vaping.
TC devices for the most part use PFM when in a tc mode, kinda similar to PWM.