Assembled boards arrived today (from PCBWay). A quick test reveals I didn't screw up as they worked perfectly, including the RGB.

The 2040 having more available GPIO's simplifies the design process and with the driver:vendor option RGB is a breeze and the flashing is easy with drag and drop, definitely the way to go for your first keyboard project.

One thing for certain, without a microscope or camera with zoom, hand soldering these tiny devices would be a major challenge for anyone and not recommended for your average hobbyist or old engineers like me.

The cost of 5 boards (3 completely assembled and 2 empty), including courier amounted to $87.34. That's about $22 per assembled board which is as good as it gets... I should have got all the boards assembled, I will in future.

Next Step:

It would be tempting to just add the electrons from the dev board to the main keyboard PCB and call it a day, but as I now have 3 perfectly good RP2040 Keyboard Modules, I think I go with a basic keyboard PCB, that is a board with only the switches, diodes, RGB leds and the 30 pin connector. This also has the advantage of being able to repurpose it for use with other modules.

There is no difficulty in hand assembling the bare-bones board as the diodes, hot-swappable connectors and RGB are easy enough to hand solder, thereby reducing the overall cost.