This app was mentioned in 8 comments, with an average of 2.88 upvotes
Microsoft Groove supports playback from OneDrive - they recently discontinued the attached music purchase/streaming service, but the Groove app is still around for now.
https://play.google.com/store/apps/details?id=com.microsoft.xboxmusic&hl=en
An app that plays with the screen off. Backlight chews battery, even on low. Updating the screen does as well (I think even with regular LED, I know its particularly bad with OLED).
Or just use spotify/pandora. Or Groove Music if you are as hard for whatever Microsoft shits out as everyone around here.
If you want to also keep a cloud backup, you can use either Google Play Music, or Microsoft's Groove Music (and OneCloud).
Both are simple. For GPM, just go to the website and choose to either upload through browser, or download the client and sync multiple folders. Then on the phone just open Play Music (it is preinstalled), and voilá, your music is there.
OneDrive and Groove is similarly simple. Just upload your music to your OneDrive, specifically the Music folder in the root of your storage area (if it doesn't exist, just create it). Then download Groove Music either from the Play Store or from APKMirror. Sign in with the same Microsoft account, and you're done.
Sidenote: Groove sometimes might mention that it requires the Music Pass for any kind of playback. It is incorrect, playback from your own OneDrive storage is free.
Yes, literally one of the first applications you'll have.
Yes, you can sync up with the butt.
https://play.google.com/store/apps/details?id=com.microsoft.xboxmusic
Not as good but still there.
https://play.google.com/store/apps/details?id=com.mxtech.videoplayer.ad
Plays almost literally anything with this
https://f-droid.org/repository/browse/?fdid=naman14.timber
Material design.
Ok I've just spent a whole 4 minutes I would think that that's enough.
I'll just copypastaa from the sauce:
Yes, literally one of the first applications you'll have.
Yes, you can sync up with the butt.
https://play.google.com/store/apps/details?id=com.microsoft.xboxmusic
Not as good but still there.
https://play.google.com/store/apps/details?id=com.mxtech.videoplayer.ad
Plays almost literally anything with this
https://f-droid.org/repository/browse/?fdid=naman14.timber
Material design.
Ok I've just spent a whole 4 minutes I would think that that's enough.
Why not just keep using groove?
https://play.google.com/store/apps/details?id=com.microsoft.xboxmusic
I dunno what other music apps can do it, as I only use google music. Why not download the XBM app and give it a try?
Regarding the watch as a remote - if the app has been updated to support android wear, that shouldn't be difficult.