It should be possible to emulate the GameBoy sound chip on PSG (noise) + SCC (2x pulse + wave).

Additionally the Gameboy DMG has some built-in envelope generators, for volume on the noise and pulse channels, and one for pitch on the first pulse channel. Each channel also has a mute counter. Due to this the emulation needs to be ticked by the timer (somewhat similar to #36 but low frequency).

See: https://gbdev.gg8.se/wiki/articles/Gameboy_sound_hardware