Hi @sanjith ,
So SPI support is still under development. So right now the code (binary running on the Myriad X) and model are still being loaded over USB.
And then the SPI communication is done after the device is booted over USB.
So we are in the process of ordering future designs which will allow DepthAI to boot over NOR flash (and then also eMMC, but a different model). See here for example of a board with integrated ESP32 and NOR-flash boot. And then we also do have extremely limited number of NOR-flash-boot samples for interfacing with other embedded systems now here. The high price is temporary while the stock is so low... we don't want to stock out.
So later there will exist the capability for a SPI controller to load the neural network and binary code to DepthAI over SPI. We have not written this yet.