Hardware key and Microsoft account authentication.

Question

I want to use hardware keys to secure my Microsoft account. This is a private account. I managed to register two keys: one main, and one backup. I have set up two-factor authentication, but Microsoft has never asked me for the key during login, only for a password and a traditional response from the authenticator, even on completely 'foreign' machines. The attempt to set up a passwordless login failed because my authenticator fell into a 'lock screen has changed' loop and there is no way to approve this option. My question is, what is the point of the hardware key if logging in still happens the old way? What are the possibilities to limit login methods only to the hardware key, main or backup?