I believe you can have whatever auth mechanisms you explicitly allow. You will get prompted to use the key if you enable it, but you can also select alternative authentication methods when prompted for the key.
You can't have a security key as well as the new Prompt method.
Was anyone talking about Google Prompt? It seems like
bb88 was talking about Google Authenticator, and drewg123 was definitely talking about Google Authenticator.
Nope, the phone authentication prompt.
I have this. It even knows that iOS isn't supported and doesn't ask for Yubikey but Google Authenticator code.
What makes you think that?
Because I have a u2f key, and you have to disable the phone authentication in google.
I have a U2F key and had to go out of my way to get rid of phone authentication.