I want to know if it works in countries where it's not sold. It's the same Internet, so it should work. Right?
Google Home can be set Up and used in other countries. This Beebom article provides a step-by-step guide of doing so.
During setup you'll see popup:
You may see a warning telling you that the Google Home was manufactured for a different country, and may not work with your WiFi network.
"May not work with your WiFi network" could happen if your 2.4 GHz WiFi router is set to use one of the channels beyond channel-11, so that is one aspect.
Now coming to services, users have reported on forums that music services like Pandora, Youtube Red and Spotify do not work for them. But, that is due to these services not being geographically supported in all countries.
I guess maximum number of services may be blocked in China due to government policies. Even searches may be affected.