I remember someone posting something about their garage opening whenever they open safari, as Safari replays GET requests from open tabs when it is un-suspended, although can't find the post right now.
Basically, they had your setup exactly, but they leave the tab open in Safari and whenever they open Safari to browse the internet, the garage door opens.
I didn't dare to hook up Pi with garage opener as well. Our gate auto-closes after a configurable delay, but garage does not. If I trigger the garage opener by accident while I'm not at home, the garage stays open for anybody to come in and take stuff. So I'd need some sort of "is garage currently open" sensor, but I want to keep things simple.
Basically, they had your setup exactly, but they leave the tab open in Safari and whenever they open Safari to browse the internet, the garage door opens.