Just wondering if its anyway possible to use Authy with various services without an SMS phone number for security purposes?
Some sites only accept Authy and not Google authenticator. What I am worried about is the social engineering hacks and someone getting my number and getting my 2FA.
Not to my knowledge. This was a common request at CEX that we could not assist users with. To be fair, the type of social engineering attack that you are describing is rare, and can be mitigated by setting up extra account security (multiple passphrases, yes you can do this just ask) or you can put a notation on your account to only make changes in person at a store with an id. After all that, if something should happen to your account, they have pretty much walked into the civil lawsuit of the century due to gross negligence.
To avoid all that, just use Authenticator. way easier, way more reliable.