I want to try this board with an unrelated project on a Raspberry Pi. Nobody other than you makes a breakout board with a BG77 at a reasonable cost.
How hard is it to gain access to the UART pins? Is there an easy mechanism for doing so without using the USB port? It looks like it’s designed to clamp to something, but I can’t tell. I just need them on my breadboard.
AFAIK the UART pins are not exposed to test points and seem to only be available on the integrated connector. That said you probably could get away with connecting it to a WisBlock Base which exposes TX1, RX1, IO1 and IO2. (IO1 is the PwrKey required to turn it on; IO2 is required to power the GPS part.) The WisBlock Base would also take care of properly powering the RAK5860.
I’ve just tried this myself and found that VDD is floating without WisBlock Core installed (which is by design). VDD is used for the level shifters (on RAK5860) for TX1 and RX1 and needs to match the voltage used by the external core. In my case the external core is an ESP32 so I’ve connected VDD to 3.3 V.