Using all ten capacitive touch inputs on the ESP32
is there a way to change the pinmode from digital-in to touch-in once normal boot has completed?


You already are. However it will make no difference since that pin is connected to external hardware - namely the button and a pullup resistor.

You cannot have touch inputs connected to anything else.  The only way to get the touch to work on that input is to physically remove the pullup resistor and even maybe the button. Touch inputs are "touchy" about what else is connected since even a button that's not connected to anything else can effect the capacitance on the pin.