> The Neural Engine is dark silicon on most devices I've seen

At the very least it's used by the Photos app[1]. Likely other Apple apps too.

[1] https://machinelearning.apple.com/research/recognizing-peopl...

I have a little rust script that uses the built in vision toolkit to do ocr of pdfs, it spins up the ANE to a full 1W compared to 0 as measured by the power profiler. So it is used!

IMO, It’s a very apple strategy, stuff just works and is slowly more accelerated/lower power.