It would be helpful if in the user overview the admin could check which of the other users have 2FA enabled already or to just enforce it.
Thanks for the idea!
Two-factor authentication is an account-level setting. Once it is enabled, your account users will need to authenticate with 2FA before they can log in again.
You can export your list of users and view when they were "Last active". If that date was after the date you turned on 2FA, then they are using this authentication method. While the others have yet to sign back in.