Power Platform service admin and Dynamics 365 service admin can basically see all instances on Power Platform Admin Center.
The customer would like to manage admins to exclusively provide their minimal privilege, like Dynamics 365 service admin can only see Dynamics 365 instance.
Dynamics 365 admins is restricted by using security group, but sometimes it's hard for the customer to use security group for their operation.
It would be much better if global admin can designate each admin to manage their minimal instance.