A can of tuna mixed with sweet relish, mayo, salt, pepper, and a few minimally salted crackers.
Red seedless grapes.
Imitation crab meat with cocktail sauce on the side. Maybe cheddar slices or olives on the side.
I consider these healthyish at the moment.
Poweramp. It's easy to navigate and lets you modify the tags like artist, album, track number, etc.
If you're on GrapheneOS, you can deny internet access and when your free trial runs out, just clear cache data and you can start your free trial over but that also deletes your playlists (but not the files).
I just bought the full version tho because it's the best music player ever.