I'm also utilizing the Zooz units for my washer/dryer notifications. I leave them on all the time and have them configured to turn on after a power failure. They've served the purpose quite well. I'm also using them to track the changes in my incoming voltage to the house. Was somewhat surprised by the variability, nothing too significant(4-6v), just surprising.
I'm using a rule based on ogiewon's rule above that has been tweaked a bit to turn one of two accent lights on when either the washer or dryer is running. Blue is when the device is running, changing to green when complete, finally turning off 2 minutes after complete. It'll also send a notification to the phone of whoever is doing laundry. (Thank you ogiewon, this has provided for a high WAF. My previous attempts had been less than perfect.)