I found yet a new tool to make music on the GBA! It's a MML compiler named mmlgba. It seems promising as it's written on its GitHub page

it can handle both PSG and PCM samples.

The problem is that there is no documentation for using it... As it's based on mmlgb on the PSG side, I think it's possible to use the mmlgb documentation. However I have no idea about how to use the PCM channels.

I am a total n00b with MML, is there some kind of general convention for loading samples in a song? SuperC

has a command called '#tone' for this but I don't know if it's the same with other compilers.

mmh I decided to give it a try but I can't compile the app because of an implicit int error :/