Last year, Amazon launched a new announcement feature for Echo devices, and then expanded it to Sony-compatible Sonos speakers. Now, the function can be used on all devices that use Alexa.
The feature essentially allows you to convert your Echo devices into an intercom system, and was initially released to Echo, Echo Plus, Echo Dot, Echo Show and Echo Spot. Users send their announcement saying "Alexa announces that / warns everyone / transmit …", and your message is sent to all the devices in your home network at the same time.
Amazon says the ads are "available for Alexa's certified embedded products to be deployed and new ones to pass the self-tests and certification provided." Now, the function will transmit to any device you have in your home that is compatible with Alexa, such as an Amazon Fire TV Cube, Sonos speakers, the Facebook Portal and others.