There's another handheld that needs netlist sound, Coleco Galaxian. It has a sound effect when an enemy dives down. Kevtris made photos of the PCB but one capacitor is hiding in the photo, and some resistor color bands are hard to see. It also has a weird "PUT" transistor that I don't think MAME supports.
PUT is a so-called “programmable unijunction transistor”. It isn’t really a unijunction transistor at all, it’s more like a kind of thyristor (NPNP construction). I believe you’re correct, MAME lacks a suitable device right now.
