Even the current implementation allows Authy. It isn't great, but if you copy/paste the link that the "2FA Activation Link" gives you? It's an OTP link you should be able to paste it right in the TOTP secret field. Bitwarden has the capability, I'd be surprised if Authy couldn't parse that link.
That isn't why for me. I'm broke and unless you actively work to remove your number from databases and whatever... that kind of privacy is an illusion.