Slight clarification: It’s battery powered and has no energy generation or harvesting capability.
If we're going to gatekeep "self-powered" this hard, might as well clarify that energy cannot be created.
Let be honest though. Do you really consider something like your phone "self powered"? I know I wouldn't. My light switches that are powered by the click, those I would.
There's much more information in the linked github repo at https://github.com/krauseler/muxcard
It even includes an eInk display as well as the battery.Insane, but really impressive.