Hi atmz, if I’m not mistaken, the grantee who initiated an emergency access request and doesn’t have a premium account won’t be able to generate the Time-based One-time Passwords (TOTP) with his Bitwarden apps, but he can see the Authenticator Key (shared secret) that is used to generate the TOTPs.
So, as tgreer mentioned before, the grantee could just copy this key/shared secret into an authenticator app of his choice to then generate the TOTPs.