[pslam]

The missing piece here is that WiFi/Bluetooth/GPS chipsets ARE usually using ARM CPUs internally. GPUs generally run a funky DSP-like core but there's still some kind of OS scheduling tasks and running code to interact with the main CPUs.

The cost of laying down a fully-fledged CPU has reduced to the point where it's simpler and less risky to use an off-the-shelf ARM core (or similar), instead of a big bunch of hard logic combined with coefficient. And most of those CPUs have some sort of runtime, which is an OS, depending on where you draw the line on that.

[tmzt]

Or MIPS or other isas, but still fairly powerful CPUs.