I have recently been working on adding SMS support to my GG emulator, and there a few (very minor) incorrect details, because often reality is a bit more complex, and adding them to an article might obscure the point.

On mappers: this forget about 3rd party (non-sega) mappers like Codemasters' https://www.smspower.org/Development/Mappers

On resolution: the SMS can have a higher than 192 pixels vertical resolution: https://www.smspower.org/Development/Modes ; and some (Codemasters, again) games did use that: https://www.smspower.org/Tags/Extra-Height

On ROMs checksum verification: no need to guess, this is documented depending on the BIOS: https://www.smspower.org/Development/BIOSes

Nevertheless, I loved the comparison with Famicom's hardware design.

Last but not least, don't forget about sverx's devkitSMS for writing SG-1000, SMS or GG software: https://github.com/sverx/devkitSMS