well, i think an autonomous computer can be pretty useful. i mean, i used computers for 12 years before i got internet access; the closest i got to networking was dialing up bbses

maybe if you had a speaker you could do ultrasonic communication with ble-like range; there are several megahertz of spectrum there that can propagate through air for a few meters, and milliwatts might be adequate. similarly with infrared; historically it's suffered a lot from highly directional interfaces that assume stupid, fragile encoding schemes, but we have enough compute now to do better