You don't need to pay that much to keep a US number for use abroad. Convert any 2fa you can to use an app like Google Authenticator, then convert your number to Google voice. You can get text messages for free using your old number that way. If you don't want Google involved at all, there are many other time-based authentication apps and you can use www.tossabledigits.com for texts.
The problem with your idea is there are lots of services that blacklist VoIP #'s like Google Voice from being used for 2FA. They also don't have modern 2FA options like TOTP.
