Amazon just enabled Guard for my Echo devices.
To summarize, when you leave the house just say "I'm leaving" and Guard will be turned on. You can enable specific features, such as glass break sounds, smoke & CO detector sounds, and Ring devices. Guard can turn on/off lights when it is night time and you are away so it appears that someone's home. When you first enable Guard, it'll take you through the initial settings where you can enable or disable certain features. If you enable a feature, it will default to be enabled for every device. For example, if you enable glass break sounds, it will be listening for that on every Echo device you own. If you enable automatic lights on/off, every device that is a light will be part of that. Once you are done with the initial settings, you can go back to the settings and pick and choose which devices you want or do not want to be part of the Guard system. I have cabinet lights that I do not want to be part of Guard so I just unchecked it in the settings. I also have an Echo Dot in the car that I don't want to be a part of Guard so I unchecked that too.