My memory is not serving me well, but I barely remember (maybe 10 years ago) a news article about a family that made their own computers and operating system etc. It was most probably from Mexico (or another Latin American country). Anybody remembers?
I have read that site for two minutes and it's one of the most fascinating things I have ever read. I have never heard of this but it's definitely on my list for further exploration.
Also, Oscar Toledo made nanochess and other boot sector programs: https://nanochess.org/