My garage door opens when I say, “Alexa, open sesame.”
I have an Alexa routine associated with a SmartThings virtual switch, associated with my TRIGGERcmd trigger that runs a command on my Raspberry Pi that tells a relay to complete the garage door button circuit for half a second to signal my garage door opener to open the door. Boom!
Paul Hibbert does a good job of explaining the new Alexa routines here.
I explain the Raspberry Pi / relay hardware setup here, but there are probably better tutorials on setting up a Pi to flip a relay.
This shows how to use TRIGGERcmd with SmartThings.
Bubba also has some great videos explaining the process. Here's his latest video.
This is new for Alexa but I've been saying "open sesame" to Google Assistant for a while now. I like Google Assistant because I can use her on my phone, and it's easier to setup because it skips the SmartThings step because Google Assistant shortcuts can be used with any voice command. Alexa's routines only work with smart-home commands.
If I missed anything in this article, please let me know.