Existing PIR Sensor thats not smart

I have a Bathroom mirror that has a sensor you wave at under the Mirror that turns on a heated Mirror and LED lights.

Does anyone know I would change this so a Zigbee Smart Sensor without butchering the Mirror as its a closed unit? I had thought that I could put a Sonoff Zigbee 2 switch at the wall connection but the PIR sensor starts off in Off mode.

Do you have the vendor name or a model number available? It would greatly help.