We're basically talking attritable devices being needed and protocols which make them useful - i.e. something you can release that stands a chance of getting information out before its destroyed and where the users are nowhere near it when it's launched.

EDIT: I mean realistically you basically would want to just toss a handful of cheap USB memory sticks out across a city.

So if we're being realistic it's just more USB-C OTG devices. Ideally what you want is it to become standard for USC-C memory sticks to have a USB-C port on them so they can be daisy chained and copied stick to stick if given a power source so they're easy to copy and spread.