You're on the right track here. Garage doors are a security risk and safety hazard. All these homebrewed, cobbled together solutions aren't tested to UL standards like the official stuff is.
> You're on the right track here. Garage doors are a security risk and safety hazard. All these homebrewed, cobbled together solutions aren't tested to UL standards like the official stuff is.
How so? I don't think anyone's talking about a homebrewed garage door opener, just a hacked garage door opener remote. It would almost certainly be physically and electrically isolated from the actual UL-tested opener.
If you're doing homebrew, a pretty easy and effective solution to the "state" problem is point a camera at the door. That also gives you better (remote) situational awareness when the door is going to close than any commercial solution on the market (though I haven't actually checked what's available in 10 years).
I actually built a IOT garage door remote about 10 years ago (I got the hardware working, but lost steam with the control software beyond running commands over ssh). The effort I spent to directly sense the door state was a waste. You've got a good solution with a Raspberry Pi, an off-the-shelf remote, a reed relay wired to one of the buttons, and a webcam.
But ultimately, the best and cheapest solution is neighbors who will help you.
Maybe some people in individual houses watch and wait for their door to be fully closed before driving away, but that doesn't seem to be the norm for collective housing (I've certainly never cared myself) or even for most individual garages around here.
They have pressure sensor strips along the bottom to detect impact that's not the ground, to make this reasonable.
It's not some new idea, it's the current state of all of these remote doors.