For dead drops, beyond worry about viruses there is also the concern about physical security so you don't fry your device/port. Randomly plugging in unknown USB devices just has way too many downsides.
Micro SD may be safer, it’s hard to fit any large capacitors in there. Bulk cards are still not that expensive in smaller sizes.
Wifi captive portals with simple file sharing are probably the safest way to go. You could also locate it in a hard-to-reach place, or completely out of sight, to make it hard to destroy. My favorite idea is to fit a tiny ESP board inside an outlet box.
Wifi captive portals with simple file sharing are probably the safest way to go. You could also locate it in a hard-to-reach place, or completely out of sight, to make it hard to destroy. My favorite idea is to fit a tiny ESP board inside an outlet box.