You've got it half right. They're not actually trying to break into your account, they're trying to get a US phone number, while overseas. Google voice has fraud blocking features that prevent people from other countries from easily getting US numbers, ESPECIALLY if they get reported for scamming.
They basically are using your real phone number as a verification for Google voice, and you would probably never know. Google would give them their own phone number, that they would then use to try to scam other people. You are just being used to get an account set up.
My wife buys things from Facebook marketplace sometimes, and I use my Google voice number to hide my real phone number from scammers. What's funny is that when they ask if it's cool to send a code, I always say yes, because when they try to use my phone number it already knows it's a Google voice number and won't let them do anything with it. I basically just waste their time.
The other variation on that scam is a little more serious, if somebody already has your username and/or password for your bank, they can request a password or 2fa reset code, and then you will inadvertently relay it to them. However, you would have to be specifically targeted for this, they would already need account information, Plus, it would come from your legitimate bank, so you should realize it's probably not something to send to somebody else.
