I would set up your router, turn off ssid broadcast and forget about it. It’s doubtful they have the equipment to find an access point that doesn’t actively announce itself to the world .
Edit: it means you will have to manually add your wifi network to your devices by typing in the ssid on them but other than that there shouldn’t be any issues
That is using messaging for the web through Google Fi. But there is little reason to do that now as Google messages the app itself can be used through messages.google.com. there are several stand alone computer applications that use the portal as well (messages in the windows store, messages or google-messages package in most distros. Dunno about Mac. Either way, instead of fi being the backend, the app connects directly to your PC. You just have to pair your phone using the app directly.
Maybe it depends on the access point. When I turn it off on my router there are no beacons sent. Unless you specifically probe the ssid it doesn’t announce itself. BUT granted when you make a connection the ssid does show up during the handshake. If you were watching at the exact moment of connection then it would be detectable. I suppose they could use a mass deauther device and cause new connections and detect while that is happening but they they would need to triangulate the location of said ap… Again a lot of extra equipment.