While working on that I also thought about an alternative simplification: use physical switches and LEDs but aggregate them.
Over some recent rainy Winter weekends I created a not-very-pretty proof of concept. KENBAKless uses a 4x4 push-button matrix "keyboard" and two NeoPixel strips (all squeezed onto a shield):
With some crappy paper labels:
A downside is you lose the physical alignment of the buttons and LEDs.
On the upside, I implemented an Octal mode for entry, for example pressing 0, 3 and 2 sets the display to 032 (0b00011010), rather than 0b00001101.
There's one extra button, I called it "sys". It’s used to set LED brightness, colour and Binary/Octal input mode. There are extra LEDs, I use one to indicate Octal.
A short video: YouTube
I'm done, I’ve scratched that itch, now I can move on :-)