Apart from the rich text field, it seems as though the majority of fields we can generate inside of Collection lists can be managed from a smartphone.
The way I am developing my project (blog) will allow me to just focus on adding content to collections and not needing to design much. Making an app that would only allow managing items would be huge! I could be completely mobile and add posts, pictures and links on the fly. Not sure how wishful thinking this is but thought I'd share.