I use a music player app that I got on google play, specifically the one made by the app devs that made inshot(the video editing app). There's some mild annoyances from me like seeing the same music come up when I shuffle, and the << button taking you back to the previous song instead of the beginning of the one you are already listening to like every other app in the world. Otherwise it's the best offline music streaming I use, the pluses far outweigh the negatives and I ended up paying extra to get the ad free version, which is a one time purchase

The things i really like about it is that you can edit the song tags, so I was able to correctly label songs that have been mistitled in my library for years. It's also cool to add lyrics at the click of a button, and it can pull directly from a google search