There is no standard sound/music format for Virtual Boy games. Maybe some games share the same format (for example, if they are from the same company), but at least some games have their own unique sound engines.
Well, I was wrong. The VGM format has supported VSU data since at least 2016. VGMRips has rips of a few games made with a modified version of VBjin. You can, for example, listen to Golf’s demo music without the accompanying sound effects.
Note that VSU emulation is still not perfect; there’s at least one track in Panic Bomber where the percussion sounds different on hardware, if I remember correctly.