Gee, I would have expected M2 to allow any messages in folders. Though you couldn't "move" them (meaning also hiding them from the original feed) and you might need to enable "Show Feeds" in the settings for that view. Grouping feeds - not in M2 though not a bad idea if you have a large number of feeds. Not that I couldn't cheat, possibly. I have reordered the list in the panel before (by manually editing a file), not 100% certain I could move feeds inside other folders though.
