I was taking my door panels off so I was curious if this mod would work for me.
For reference I have a 2018 ES 5sp WITHOUT Heated seats and mirror signals but I DO HAVE the wiring for heated seats.
First inspection showed the pigtail on the door is missing both of the extra wires as stated by OP.
I decided to follow the loom into the car and under the dash and see if maybe it would be back there.
With both sides the loom splits into 2 pig tails and upon inspecting these I only found a single extra pin on one of the pigtails.
On the LH side the extra pin is a red wire and on the RH side it is a brown wire.
I would be curious to know if this is for the turn signal light or something else going to the door.
Unfortunately I would need to take the dash off to follow the wires more.