Huge issue with those having to use a phone from one country with apps local to another country - very common for extensive travel, as the formal Google play store locality change is only allowed once per year.
That's been available on their site for as long as I can remember. Long before they had an app that would tell you as well. Heck, I'm pretty sure before Twitter even existed.
2. You run the risk of losing Google voice, if the main US account is switched to another country where they do not provide voice services