That's all fine and good but it would be nice even if we just replaced the plastics used in PCBs with something that can biodegrade and/or renders itself harmless after going into the waste. Truly biodegradable electronics would be ideal but even minor improvements would make a big difference based on the sheer amount of electronics that get manufactured and distributed across the world every day.

I remember reading about using magnesium instead of copper in PCBs a while back. I wonder what happened to that? Magnesium tracks on a fungus-based substrate would be fantastic (and neat!).