Thank y’allI believe TM will back up all users. And it should restore all users if you take the first opportunity on the first boot to let it migrate back. At that point the new iMac should import all things from the backup and restore all accounts. At least that is how it has worked for me.
Thank you SlyTime Machine does back up all users. If one uses the Migration Assistant utility, individual users/files can be chosen for selective backup.