Back to the proverbial mythical drawing board. My original idea of bundling the STM32 with NRF52 was a dud, even though I'm quite certain it would have worked, however, the complexity of combining all components and writing two separate firmware branches would be effort-prohibitive at that point.  I have a real job, I cannot afford such a full-blown full-time effort at that point, safe for hiring a small team of SW/HW devs to finish this. Therefore, I made an executive decision to scale back a little and go native.

We go full commando! Redesigned the PCB and came up with an amazing ultra-super-nano small board.

Off to manufacturing!

Almost manufactured, SMD-ed right now. Crossing fingers. Will get it next week.

As you could see I dropped the STM32U and went nRF52 full native. Hence the massive pain in making sure the SPI worked to drive the display. Worth it!

Probably the smallest PCB I've ever designed, 8x8mm, 80 micron traces.

It's 10x10 with the antenna.

I could make it even smaller with a dual-sided design but not sure it's worth it.

Final design should be 2-layer single-side flex PCB however we cannot go that low before we confirm the correct functionality. I'm not sure my antenna calculations were correct. However, as long as I get like 10 feet / 3 meter signal propagation I'm golden.

Definitely worth exploring a chip antenna, however, at that stage it's a total overkill.