I decided to start with the keyboard. To avoid designing a new layout from scratch, I decided to clone the BlackBerry keyboard as closely as possible.  A standard Blackberry keyboard contains 35 keys. I decided to include a DPAD with 5 keys. To save GPIO, I decided to place the 40 resulting buttons in an 8x5 matrix.  Because special keys will be accessed via shortcuts, the keyboard must have N key rollover. This is accomplished by incorporating diodes alongside the buttons. Next, I chose the cheapest components from Mouser and got to designing the PCB in Altium. I have ordered the PCB from JLCPCB in order to test the design. I think that I will use a raspberry pico as a keyboard controller. I am currently waiting for my parts to arrive. I will make an update once i get the keyboard assembled