This is interesting because Car and Driver published their review of the Taycan and they wrote about how there isn't "one-pedal braking" because regen only happens when you push the brake.
There's No One-Pedal Driving
Many EVs provide enough deceleration when lifting off of the throttle to bring the vehicle to a complete stop and enable true one-pedal operation. Not the Taycan. Citing the fact that the most efficient thing to do is coast, and clearly not trusting the pedal control of its buyers, Meier said they decided to not offer much regen capability and instead wait to do the majority of regen when the driver pushes the brake pedal. There are two settings, though. The default is none, but a slight amount can be enabled, if desired.