oh, wow, making sound tracks and including them into a SGDK project and playing them is way easier than i'd expected. last time i tried to do SMS/SMD homebrew VGM was a completely impractical format for homebrew and you had to roll out your music in MML format for best data compression
aha, found the caveat, SFX is PCM only, if you want FM/PSG SFX you need to use other sound drivers entirely and those need to be composed in MML