If I wanted to do something like this I'd create open WiFi access points called something like "DeadDrop". They wouldn't be connected to the internet. Instead they'd forward you to a locally hosted site that let you download and upload from local storage.
WiFi has a lot of advantages. You eliminate the risk of USB attacks, physical damage to the device, and the actual location is unknown. The downside is that it would require power.
WiFi has a lot of advantages. You eliminate the risk of USB attacks, physical damage to the device, and the actual location is unknown. The downside is that it would require power.