In order to share document with Notion for desktop, it would nbe great to be able to synchronize some documents to a remote storage: ideally one should be able to decide on each document the synchronization type (left to right, right to left or both) and the target (cloud storage or personnal NAS storage).
As far as personnal NAS storage is concerned the CIFS protocol is great but WebDav would be even better because it is very standard and is already suported by some iPad applications.