I don't know how much interest there is in using the Amazon Alexa powered devices to control the HAI but I have successfully been doing this for quite some time. In a nutshell, I run the Amazon Echo Bridge on the server with HH. The bridge permits you to control devices that you define by recognizing a name (e.g. garage door) and opening a URL that you specify. I have some devices defined and URL's which when opened run the code to authenticate to HH and call any API feature. If anyone needs more information, let me know.
It would be lovely if the next version of HH/Spaces had this functionality built-in using an Alexa app (as well as Siri integration).