Currently, you cannot select can copy documents from a hub. In order to interact with them, you need to select the folder or file and it takes you to the document. This means if you want to create new collections of documents, there is no way to interact with all of them unless they are in a folder together, which eliminates the purpose of the hub in the first place.

TLDR: Ability to view details of files/folders directly from the hub as well as copy from hubs