I’m originally from Brazil but I’ve been living in Poland for the past decade so I had the Polish app setup with Android covid notifications. The neat thing is that it doesn’t matter as they all talk together due to how the protocol works.

I got a few notifications in Poland, and I also did travel to Brazil, and got notifications there too.

The app only works if enough people are in though, so if nobody uses then it won’t work. Depends on the area, people, way of thinking.