How can I see only the name alias as opposed to the normal display name for devices and interfaces?
Simply make sure the user's assigned role has the "View Item Name Alias Only" role right. The User Settings > Item Name Display Setting selector is controlled by the "View Item Display Name or Name Alias" right. It uses that selection if they have that right. Take that away and give them the "View Item Name Alias Only" role right, and it always show alias and ignores any saved setting for the viewing option.
Additional information about changing user settings: