Not deep down in the nitty gritty but only general top level ideas from a general user point of view, like for instance reducing the maximum length to considerably reduce the manufacturing costs. In fact I think with the current size you will get two PCBs for the cost of one (if the width is kept at 50mm..or a few microns less).
Although I have had previous experience working with MCUs (50 yrs ago...gosh I feel old, but I was quite young then) at the assembler level, in recent times I have produced drivers for things (
see here) but they have tended to be add-ons rather than at the MCU level.