Within the last couple of weeks Amazon released a new Application Programmer Interface for Smart Home skills. This contains support for the kinds of actions you are inquiring about. Here's a link to the section of the API that deals with sensors:
https://developer.amazon.com/docs/smarthome/build-smart-home-skills-for-sensors.html#discovery-for-sensorsThe issue that is not yet clear, at least to me, is whether or not you will need to have one of the new Echo Plus's or Show's for these commands to work in your system. Both of these new devices, which start shipping next week, have their own Zigbee hub builtin to them, and obviously, will support the skills with the new API. But I am guessing that older Echo's won't support this functionality.
I currently have a 1st gen Echo, a 2nd gen Dot, a 1st gen Show, and a 2017 8" Fire Tablet with the new Show Dock. I'm planning on adding the 2nd gen Echo Plus to my setup, which will then become the Zigbee hub for the entire system and (I'm hoping) allow all of the functionality from the Smart Home Skills API to work thru out the house.
However, I'm waiting for a month or so after next week's release of the new devices before I order. I want to be sure that there aren't any "unresolved issues" with these devices before I jump in with both feet.