To aid with debugging, I'm channeling serial output from the target nRF5 out over one of the unused pins of the IDC 10-pin programming header. My two most recent nRF5 breakout boards are wired to do this. This little adapter allows for output Serial to be read using a regular FTDI serial adapter. I decided this is preferable to putting a 6 pin FTDI header on the target module itself, which is what I did earlier with the Ebyte nRF52832 breakout board.