Like being able to add and remove instruments to a song depending on the current area or situation, in a similar vein to how Hollow Knight does it for its areas, or Paper Mario with how Toad Town's bg music completely changes without having to restart the entire song upon entering places like the fortune teller's house, or the badge stand.
I have absolutely no LunaLua knowledge, but I'm curious about smth like this being possible before diving in and trying to learn