A keyboard was available from Catapult for quicker typing. Anyone who's written XMAIL with a gamepad will tell you how sorely that's needed! It's even rarer than the modems, likely only available via mail order. The production keyboard is made by DihShin (aka DSI), who is still manufacturing similar keyboards. A prototype keyboard was also made using a board that looks like the Qtronix QX-083. According to the source code, a Samsung 88C0504 microcontroller was used for both keyboards to . This runs the SAM8 instruction set, who's documentation doesn't seem to be available anywhere publicly.
A PS/2 to Genesis keyboard adapter has been developed by Geoff Ledak using the STM32, available on Github.
