2FA RFC 6238 with custom authentication app

I want to add standard 2FA (RFC 6238) to my account and don’t want to use the blizzard authenticator application. Can you help me please?
SMS verification proofed to be not secure. So I want to use only my own free and open source authentication app according with IETF RFC 6238.
May be I don’t want to use your proprietary app on my phone, or I even don’t have a smartphone, you shouldn’t care about the reason and respect people rights for securing accounts. So at the moment I have to leave my account without 2FA until you implement such a simple security feature. Thank you.