I tried this a few years ago, it only worked for American customers. But it did save me some money making calls. Last I checked they basically abandoned their mobile app for a near decade...
I think GV is limited to US numbers and you have to have a US number to sign up.
It places a burden on my contacts who want to send an sms because they have to use international rates. But it’s better than not being able to text me.
However, installing the Hangouts client will let you use it as a better GV app for every day use (messages/voice, for settings and stuff you still need the GV app or the GV website).
At least until Hangout dies ...