I have a magnetic Zigbee vibration sensor on my washer and dryer connected to Home Assistant. I hadn't thought of monitoring smart outlet current/voltage instead, that's a good idea too.
The machine does have an app and Bluetooth, but I can't see the point of spending the time reverse engineering the protocol, and the app is never going to be activated on my phone because it wants access to camera, sound, phone and my contacts list.
Edit: It seems some integration work has been done for HA: https://github.com/home-assistant-HomeWhiz/home-assistant-Ho...