How plausible are animated versions of these in real life? What's the thinnest we can make a display+processor combo that can be powered by, say, the heat from my hands?
I don't think you could practically power a display + processor combo with the heat from your hands. The best I can find on the power radiated by your hands is this article
That article says you can get about 5 milliwatts using a Peltier converter, so working backwards based on Peltier converters being ~10% efficient that's only 50 milliwatts radiated by your hands. Even with an ideal 100% efficient converter that turns 100% of that energy into electricity, combined with a 100% efficient step up converter to raise the voltage that's not a lot to work with, that's barely enough power to light a couple of blue LEDs, much less a display and a microcontroller capable of rendering 3D graphics.
What if it's just a display plus a wireless receiver? SMartphones have not shrunk much over the last decade but that's cause of the constant pursuit of more functionality. I'd be quite interested to see how minimal they could go. I'll bet on playing card-size active displays within 10 years.
https://www.smithsonianmag.com/innovation/this-flashlight-is...
That article says you can get about 5 milliwatts using a Peltier converter, so working backwards based on Peltier converters being ~10% efficient that's only 50 milliwatts radiated by your hands. Even with an ideal 100% efficient converter that turns 100% of that energy into electricity, combined with a 100% efficient step up converter to raise the voltage that's not a lot to work with, that's barely enough power to light a couple of blue LEDs, much less a display and a microcontroller capable of rendering 3D graphics.