It's easy to make a linear power supply, but a switching power supply like a charger has a lot of complications. Among other things, the layout of the board matters a lot due to the high frequencies involved. I'll point out the the application note on this controller chip is 34 pages long. https://www.st.com/resource/en/application_note/an1326-l6565...
Certainly. My point was more that the basics are pretty readily covered in intro electronics courses. Heck, throw in a low pass filter or two and you end up with a lot of the same required knowledge to make a switching power supply.
I agree you won't be able to make an apple quality device, it'd just be enough info to understand how one is working (Without taking into account things like line noise impact on wiring).
