Question about Google Nest Mini

Google Home phone function: only in the USA 🇺🇸, currently not available in Switzerland.

Google Duo: With the help of the Duo app (Android | iOS), other Duo users can be called via WLAN. These can be video, phone and group calls.
I bought the Google Nest mini as a gift. That's why I can't say exactly which functions really work.

Thank you ++++ :-)