As far as sending the notification to google home. You might be able to use google assistant relay to broadcast the information.
As far as getting the information I have done this with a virtual switch named “Tom location “. From there I have a shortcut in google home setup when I say” where is tom” it turns the switch on.
From there, I have a piston that uses the geolocation from Toms presence sensor to determine whe they are and the approximate time from home.
You need to send get requests from the piston and use the responses to push that information to your speaker. Mine actually plays on a sonos play one.