The feature where samsung gallery identifies faces in photos and them groups them together as people should be synced accross samsung devices. At the moment each device has its own set of identified people which leads to inconsistencies in the people identified and the photos used. By syncing across devices, finding the right photos that you want on any of your devices would be much easier as the same set of people and identified photos is on each one of them
Now that it syncs with onedrive however photos can be synced across devices. With onedrive sync and the addition of features like facial recognition it's moving more in the direction of a photo storage app.