I'm curious - are there any ways of finding out the precise hardware that's used in these small-scale devices that are generally not considered to be computers (like smartphone chargers) without actually having to take them apart? Are there special datasheets, or perhaps some documents for government certification, or anything like it? I've always been fascinated with the barebones, low-spec hardware that runs mundane electronic things, so I want to know where the author got all that information from.
Generally no but taking them apart to look at the chips inside is easy. Fwiw everything has a CPU in it these days. Actually that's been true since the 70s. Your old 1970's keyboard had a fully programmable CPU in it. Typically an Intel MCS-48 variant https://en.wikipedia.org/wiki/Intel_MCS-48#Uses
Today it's even more the case. You have fully programmable CPUs in your keyboard, trackpad, mouse, all usb devices, etc.