It looks like that garage door opener has developer mode that can be integrated with with smart home. According to the doc on their site, you’ll have to email them for developer key. It does give a warning though about the connection not being secure.
WARNING: GarageDoorBuddy developer APIs are not encrypted. By enabling developer mode, you agree that you are responsible for maintaining the security and control of access to your network and all devices on your network.
With that said, you can probably use this to communicate with your GDB device.