I recently switched from Homebridge to Home Assistant, and overall it’s amazing. However, one feature that I really miss is Google Assistant integration, so I can control my devices via Google Home speakers.
Home Assistant has GA integration, but it requires either HA Cloud or for the HA instance to be exposed externally, and I don’t want to open holes in my network. Homebridge does not have this requirement and it works perfectly (and the setup process is dramatically simpler), so clearly this is possible. The repo that implements it is here:
It would appear to me that your HomeBridge solution is also exposing itself to the internet, the sheer fact that you authenticate with your Google account to link indicates this.
Google assistant is a cloud service, and therefore will never work without external access granted. HomeBridge is just hiding this from you.
The GA integration with HA is done with SSL certs which I would hope HomeBridge does as well. If you want this integration you have no other choice.