To make the keyboard work with the PI, I wrote a user mode serial driver that uses the uinput kernel module to inject key events to the kernel. I've posted the application to Github. You can find it here: SerKey Serial Keyboard Driver. That was a fun project that required learning about Linux serial port programming and the uinput kernel module.

Lastly, the PI supports composite video out. This will connect to and drive the old Apple IIc monitor. However, PI OS does not provide a mechanism to turn off the chroma color signal modulated on top of the basic monochrome NTSC signal. This noticeably degrades the picture quality. So, I wrote another simple Linux command line app to properly set up the PI VEC composite video controller for a monochrome NTSC signal with no color chroma. 

You can see the improvement to the display image below.

Before

After