users.users.<name>.openssh.authorizedKeys.keys

A list of verbatim OpenSSH public keys that should be added to the user's authorized keys. The keys are added to a file that the SSH daemon reads in addition to the the user's authorized_keys file. You can combine the keys and keyFiles options. Warning: If you are using NixOps then don't use this option since it will replace the key required for deployment via ssh.