It looks like this hack uses an esp8266, which supports WiFi. Most likely the chip is booting up its own WiFi network for the phone to connect to, the phone is sending the payload over this network, and running the usb exploit. Some esp family chips should also support Bluetooth.

Okay, so the attacker would need to be within range. Is that a correct understanding?

Although that’s implied, you could use a proxy device nearby instead

"within range" can be quite far away if you use targeted directional antennas.