[bsbsjsusj]

Punchcards would be better. QR relies on machine vision. The camera would be running its own code.

That said, cameras are more of a commodity.

QR and typing: see TOTP tokens!

[marcus0x62]

The Soviets had a strong typewriter implant game[0]. They might have to revive some of their old tradecraft to either deliver implants via the card punches, or monitor what is being sent over the air gap.

0 - https://spectrum.ieee.org/the-crazy-story-of-how-soviet-russ...

[dboreham]

Paper tape is more pocketable.