The only thing on my door is a flashing light activated by switches top and bottom. The purpose of that flashing light is to indicate DONT BACK THE CAR OUT AS THE DOOR IS DROPPING. I want to now add the ability to notify, by buzzer or flashing light in the house, that the garage door is open.
I will add a magnetic wired or wireless door sensor device attached to your garage track. When door is up, sensor will be separated. It sends a notification to you. It can beep or light up another device in your house. The sensor device can be from $1.5 USD up from AliExpress.com. I have myQ device for years. When time it retired, I will convert with door sensor to signal me the door status. Good luck to you.
While I personally would over-engineer this with a distributed peer-to-peer Wifi network build with an ESP32 and a Rasberry Pi, all you actually need is a simple RF link.
Put a magnetic sensor with a wireless transmitter in the garage and a receiver with indicator in the house.
Many ways to approach this but here are a few ideas to get you started. What’s nice about these wireless sensors is they can talk to a “smart hub” in future when the home automation bug bites you. And it WILL bite you trust me.
No affiliated links… just random examples off the web.