After a bit of research there's a website which shows what steps are required to make a QR code but are a bit light on the details. Wikipedia has some info but is pretty technical. It looks extremely complicated which is why I can't seem to find anything.
The goal would be to make a QR code that has a few characters encoded (like ABC) and could be read by a cellphone's camera.
This would be a significant project and a significant time investment as there's a lot of steps and many months (or maybe years) of reading and research. Would anyone be interested in reading a post about this and if so, what information/sections would be useful? Is this a pointless endeavor? Could this be packaged up into something that could be sold?
Maybe consider going down the Paper Computer route depending on the audience you are targeting ?
https://www.techagekids.com/2018/04/make-my-first-paper-comp...