If YouTube Music is going to fully replace Google Play Music, it will need to handle many of the features that listeners take for granted -- and now, local playback is one of them. After an initial rollout for some users, YouTube Music's Android app now supports locally-stored songs for many (if not necessarily all) users in a "Device Files" section. You might not have to worry about missing out on a hard-to-find tune just because you want one app to handle both your local and streaming music collections.