Two tiny 10x10cm PCBs for keyboards

Did you know that the price of fabricating a PCB jumps at the magic threshold of a ten centimetres square? That seems to be especially true in the USA where hobbyists only use local firms for tiny prototypes, and otherwise import from China etc. You can currently get a set of five PCBs shipped from JLCPLC for only USD $5. As long as you're happy with tiny keyboards, that's incredibly cheap!

Bivvy16D (in red) and Bivouac34 (in green) PCBs

So, I ordered two designs in January - the Bivvy16D is a split keyboard with 15 or 16 keys and a 5-way navigation button on each half (so 30 to 32 normal keys in total), while the Bivouac34 is a monobody keyboard with a left and right PCB joined with a ribbon cable using "gold finger" edge connectors (with 32 to 34 keys in total). I want to make a tented keyboard with this.