ffplay plays audio-files too.
so set an emulator system for music (or use another prefered music player; like vlc)
set a keyboard event on gpio of rpi and use a coin slot/button/electrical bridge.
something like here.set your select-button (often : return) in rpi-script instead.
now you can scroll through am-list but can't start anything.
if a coin is insert in slot, the gpio hits the return-button (in AM : select) and starts so your track at current position in AM.
Instead of using rpi gpio, have a look at an old
usb keyboard controller for hitting your select-button