They're not official guidelines. The guidelines on the main page are the only guidelines. They're neat meta objectives though.
The main page has rules. My post has optional guidelines. They're not official.
As for sound, easy solution is to just make something in Deflemask.
Here's what it uses anyway:
- 2x pulse wave (12.5%, 25%, 50%, 75% duty cycles)
- 1x 32-sample 4-bit wav channel with very limited volume control (best to assume this just does on/off)
- 1x 15-bit/7-bit (selectable) LFSR noise channel, frequencies are kinda weird, if you don't do any freq sweeps you should be fine
Each channel supports hard-panned stereo (left/centre/right).
Volume goes from 0 to 15 inclusive. Not sure what the actual lower/upper bounds are on the period. It appears to be a simple voltage sum, unlike some chips which use logarithmic volumes.
For the curious, at least one pulse channel has a freq sweep unit, and I think both have a volume envelope unit each. You do not actually need to know about these as you can replicate their behaviours manually.