Cant get Midi ( .mid files) to play on clapper, VLC etc. It needs some codecs but not sure how to install the needed SF and MIDI codecs.
Would Qsynth work for your needs?
I havent tried the flathub version but the built in one that came with Bazzite does nothing
you need not only a synth software (like fluidsynth in VLC) you also need to set up a soundfont to “install” the instruments on your synth. Take a look to these sites to learn how to do it (also works in games which usee midi music)
https://member.keymusician.com/Member/ImprovingYourSystem-Linux.html