The second installment in my Nine-Bit CPU adventure
I just came across: https://begriffs.com/posts/2018-11-15-c-portability.html In it mentions the Unisys 1100/2200 and Honeywell 6000 as both using 9 bit "chars". You might want to delve into those architectures. I am tempted to explore FPGAs. Perhaps you could write up a bit more about the tooling.
You should investigate those structures further. Considering FPGAs has tempted me. Perhaps you could elaborate on the equipment in your writing. https://onlyup-game.io/