Input wise, a throat mic would work. They can rest on the side of your neck and generally only hear you. There’s probably even Bluetooth ones available out ther

Input wise, a throat mic would work. They can rest on the side of your neck and generally only hear you. There’s probably even Bluetooth ones available out there. Storage wise, I’d personally just go with a publicly stored (and archived) cryptographic hash of the recordings. Not really a need for zero trust if you can produce proof of authenticity.