If your phone has a slot for an SD card, load it up (opus sounds good enough for on the go) with your collection and you can have the benefits of an old school player behind an app interface on the phone you already carry everywhere.
Phones these days have so much internal storage that I haven't had to use an sd card, although my phone does have a slot for one. I prefer to use plex and plexamp for my music so I have the conveniences of streaming services with the ownership and classic music player feel of old school devices.
Having tried Youtube Music, Tidal and Amazon Music, I feel that the UIs of most streaming apps and even most music apps in general are not that great.
