Is is possible to lock a HR Casework ticket so only the assignee can access?

My organisation is looking to switch on the HR Case Management feature in HCM (Redwood). It does not seem possible to lock down a case so that only the assignee can access.

There does seem to be configurable workarounds (see attached) although for a case to be locked to the assignee does not seem possible if there is more than one person in the queue/resolver group or if there is more than one person in the permissions group or similar.

It seems the only real way to do this is code customisation. Any experience of this or knowledge would be hugely appreciated.