I've been using Music Folder Player (https://play.google.com/store/apps/details?id=de.zorillasoft.musicfolderplayer.donate https://play.google.com/store/apps/de

I've been using Music Folder Player (https://play.google.com/store/apps/details?id=de.zorillasoft.musicfolderplayer.donate https://play.google.com/store/apps/details?id=de.zorillasoft...) for over a decade for this very reason. I think Android has now made this type of player almost obsolete. Every app has its own file sandbox and apps must go through an abstraction for media that works poorly.