Hi @sgrunc_80 ,
I have noticed that the ZED-F9P can be reluctant to start in SPI Mode if it has previously been used for UART and/or I2C. I added some notes about this in the post you linked. Please connect via USB and try setting the Protocol In and Protocol Out using u-center and UBX-CFG-PRT: set UART1 and I2C to None; set SPI to UBX+NMEA+RTCM3. Ensure the configuration is saved to both Battery-Backed RAM and Flash using UBX-CFG-CFG. Then restart. That should get the SPI interface working.
The SPI pin labelling error was limited to the ZED-F9R board. The ZED-F9P boards are labelled correctly.
We have used SPI very successfully in the RTK Reference Station. The interface between the ESP32 and the GNSS is exclusively SPI.
I hope this helps,
Paul