2FA readiness of social media giants and tech giants

2FA or two factor authentication is a mechanism of using another means of user authentication besides solely rely on password. 2FA or MFA (multiple factor authentication) would greatly increase the security. These are the common 2FA deployed in many internet web sites:

One time password send over E-mail or SMS
TOTP (Time-based One-Time Password algorithm)
U2F (Universal 2nd Factor)
WebAuthn (FIDO2 Web Authentication)

Now, most popular social media web sites and e-commerce sites had already supported at least one or multiple 2FA …