Well first of all I missed the deadline for the Cyberdeck challenge :(
CyberKeeb is both a normal mechanical keyboard, and a cyberdeck. In normal operational mode, it sends the key strokes to the host computer. However, if a special layer is activated, it sends the key strokes to the on-board Pi Zero cyberdeck. In the future, I'll also add the feature to allow the Pi Zero to send keycodes back to the micro controller (Pi Pico) which can then forward them to the host computer, as a way to script some auto-types. Pi Pico talks to the Pi Zero via SPI, over the Inter-Board Protocol I designed. Currently I only have an implementation over SPI, but in the future will add I2C for expansion modules.