I’ve used the Phocid player on my phone (TCL with Android 12) for a while, and it was okay. Before that, I used Phonograph Plus, almost the same, also worked.
Now I want to move things like that to my new used tablet, which is a Samsung T6e Lite (this is from memory, sorry – I hope you get the idea) with Android 14. I moved all my music to a SD card, stuck it in, and installed Phocid. It starts and (after a while) lists the albums, but – no album art. I have the album art images locally, in a file cover.jpg in each album directory. On the phone this worked perfectly!
It may be that Phocid was just updated and broke this, but I’m more suscpicious of the different Android version. I remember long ago the early players needed help from the user to index and find both audio files and images. So maybe it is needed again, or maybe the system API for that changed? Anyway, those are just guesses. I want it to work 
–
Ian