At the moment in order to grant a user or group the permission to only see objects from one specific object type, it is required to:

• grant them the schema user role
• go into other object type (that they cannot view) permission setting and grant the object type user role to only the users/group that can see the other object types

This way the permission need to be applied on every object type level if there many object type that the specific user/group cannot see.

It would be better to change the way permission granularity works in order to apply the contrary such as only granting the user role permission over the single object type that user/group can see.