If you are allowing for non-legal or quasi-legal means, then most of the devices we carry are susceptible to mostly non-video privacy invasion (cell phones, fitbits, implanted medical devices, cars, etc.). Adding the Ring increases video surveillance. An Echo Dot in your home increases your vulnerability by adding another device (increasing your attack footprint), but the similar data and more could be accessed through your phone.

For example: A phone's gyroscope might be able to listen in on you, even if your microphone is off:

https://www.wired.com/2014/08/gyroscope-listening-hack/