Heavily inspired by this
A Master SystemGame Gear sound chip emulator in Pico8 using the PCM channel. Features 4 songs from SOR1&2 for the Game Gear (use leftright to select)
How it works:
VGM files are logs of register writes. I wrote a program to decode them, save what the reg settings were every 60th of a second, and RLE compress them into strings. The sound chip is basic enough to write a simple emulator for Pico8.
Limitations:

Not really an audio guy, may still be glitches
Looping only goes back to the start of the tune, rather than part-way-through as in some songs. Probably would need to decompress the songs to pico8 memory to do that, instead of my 'clever' on-the-fly RLE decoding
Noise channel is emulated (apart from the 'periodic' noise feature), but I didn't bother recording the register from the VGM file so it only uses frequency setting zero.
Bit loud
Scope placementcolouration makes it look like Alex and Blaze are having some sort of Electric Urine Battle