You can open the instance and use the Actions menu to view the XML and get the pzInsKey to include in your Product file. The instance names use the format pyOwner!pyCategory!pyOwnerType. You should be able to use the pyOwnerType value to identify the ones you want to move.
For example, here are two instances from my environment. The first one is my operator dashboard that I published. You likely will not want to move these as users may have published new dashboards in the higher environment. The second entry is a default dashboard that would apply to users who have not published a personal dashboard.