At the moment, you can only view which attachments are visible in portal from NANO.
NANO uses the default setting History private in IPK Management Settings to determine if uploaded objects from NANO are visible or not at the point of upload, but theres no way to change this for invidivual items without logging into Core and toggling the setting.
10.5 Release will include an Updated File Upload Feature that will allow analysts to be able to toggle the Visible in Portal option for attachments.