I had one of these for years before I got my current car that has bluetooth built in. I gave it to a friend of mine and it’s still in use. Lasts forever, and your phone will treat it like a headset that has five buttons on it by default (play/pause, forward and back, phone pick up and hang up), so it should work with any music playing app. I used one called Music Folder Pro which I can’t recommend highly enough.
This has better reviews than the newer version, the x3. People said that one overheated and had bad power from its USB out.