Another hardware idea that I think is cool: Hardware kill switches.
Basically, when you flip a kill switch, it cuts the power to a specific component.
https://puri.sm/librem-15/The Librem laptops use kill switches for the microphone, webcam, bluetooth and wifi.
Privacy wise, this is awesome. No-one can just hack into your system and listen to your microphone even if you thought you turned it off in software.
However, looking at their product updates, it looks like they had some difficulty adjusting their case to accommodate the switches, let alone I can't find any company that sells specific switches made for this purpose, so they probably had to implement their own design. I wouldn't know what this would mean cost-wise.
This isn't a priority, nor do I know if it's feasible with what we're trying to accomplish here, but I thought it could be a great idea.