I somehow hadn't even considered Bluetooth as an option when I read the headline, I immediately thought about INFILTRATING via audio, which also sounds insanely cool, but I couldn't possibly wrap my head around how an audio circuit would have to be set up and connected back to the cpu to pull that off.

Exfiltrating via audio also brings to mind one of those devices I really wanted to build ~20 years ago that can listen to the inside of a room by bouncing a laser beam off a window. Van pulls up in front of your house, pushes malicious code via bluetooth to speaker, which starts shrieking data it stole from the host that's then picked up by the vibrations it emparts on a window by a laser beam. Boom, crypto wallet stolen, or something... you could probably put that in a movie.