On 3/18/22, Undiscussed Horrific Abuse, One Victim of Many
<gmkarl@gmail.com> wrote:
> I would like an airgapped message composition device I can keep in my
> pocket, with a private key generated on it, and to take it to a keysigning
> party and share signatures with it!

Without radios you only have USB which is not airgap and is
full of writeable firmware and filesystem and OS and automagic.

Though displays and cameras could be used to swap
qrcodes or video streams containing such data,
speakers and mics for acoustic serial modem,
vibes and accelerometer seismograph,
LED and IR remote,
CPU heat and thermometer,
...

Mutual sensor pairings should all have libraries
and tools for doing simple data transfer via them.