For this project the feasibility study was quite long due to the interconnect method between the different PCBs. We decided to go with a strong neodymium magnet in the housing of the keyboard and pogo pins. Each part of the keyboard has a dedicated AVR micro-controller allowing it to function individually or as a part of a bigger module controlled by a master MCU.
The product has already had 3 iterations to increase reliability and optimize the form factor. Prototypes have been delivered and a metal enclosure is underway!