Hi,
Sorry about that confusion !
So the way it works is that a special config for SSH is generated for that sys_user. This basically executes a SSH command for that sys_users, and based on an associated particular ssh key permissions etc are verified.
What you described could be possible, if such configuration file is created for each user account on your machine, following same principles the whole thing should just work.
You’d need to manually setup, and adjust those SSH configurations for each user, and make sure the still generated configuration for sys_users isn’t included in your sshd configuration so it wont work for the sys_users.
Hope this is clear now.