So my configuration required, per the wiki, integration of the PDCF8563 library and the U8x8lib, so my apologies, the example doesn’t work directly out of the box without using the library manager for the sketch or modifying the tool’s Arduino library folder.
Regarding Tools->Board, I installed and use “SEEED SAMD Boards”->SEEED XIAO , not specifically mbedOS, and no reference to NRF52840. Maybe a mistake on my end. . https://files.seeedstudio.com/arduino/package_seeeduino_boards_index.json . I am on a Mac so I am certain there are a few differences in the presentation of the interface.
Regarding your findings, thank you for investigating.