This has taken a considerable amount of time to get working (over 100 hours of debugging) as verifying the SPI signals were correct has been very challenging. To give some context I first verified the spi OLED display was working using a cheap Arduino pro mini (atmega 328p) this took roughly 30 minutes. Its taken about 70 hours before any data appeared on the OLED display from the Neo. As normal more info on the blog, along with my theory of a hardware bug with ECSPI 5. This is a C application running on the M4 not Arduino code.