Just as an FYI because I haven’t seen anything here. I have my garadgets (3) working with Google Home via smartthings. Nothing extra was requried other than to setup the Garadget smartapp which I will link to at the bottom of this. Once setup and once the Google Home is setup with smartthings. Controlling the garage doors is easy by voice with no needing of IFTTT or the like.
Also if you don’t have smartthings. You can still do this using IFTTT. In some ways the verbal commands become cleaner. Using ifttt you can literally say “Ok google, close the garage door” or “Ok Google, close garage door 1”. No special words like “trigger” as with Echo or “turn on garage door 1” to open it are required. You would still use the “maker” ifttt app for the second part as described here.