I went into the offline mobile music player rabbit hole recently too. I tried like a dozen and personally I think none of them are sufficient, including Symphony.
The most important functionality for me is queuing e.g. how it works and how easy it is to use and it’s just a horrible experience for virtually every player. So disappointing 😣
Phonograph commits the same sin as every other player in that swipe changes tabs and is therefore a total waste of a premium gesture.