Wattage Sensor for a stupid Garage Door Opener, to trigger another switch

Hi, is there a sensor to connect to the mains of the Door Opener which is fast enough?

I have Sonoff Pow2. they can measure, but they are very slow.

Usecase is: If opener runs, Wattage is higher, switch another device (Light)

Workaround would be a fast sensor who can read if a contact at Opener is closed.