Hello @ferqtek
"by the speed I have", e.g. 600 kHz. Is that what you measure?
What exactly is giving you errors? Building the spi master example or running it on an ESP32C3?
What do you mean M5Stack left the default pins unconnected to the outside? Do you mean the SPI default pins? As far as I can tell, GPIOs 4, 5, 6, 7 and 10 are the default SPI pins for ESP32C3 and they are all available on the M5StampC3. (MISO - GPIO2 is not available, but also not needed for driving an LCD.)
BTW: I think you might make your life to hard. If a clock frequency of 6 MHz is what your looking for it doesn't matter whether you are using hardware or software SPI.
Thanks
Felix