CS_Pin has to be driven high on ESP32 (to be low at the SDCARD) because of some logic inbetween about sdfat HOT 3 OPEN

I can't suggest a solution since I have no idea what hardware you have.

SdFat does have an option for using a port expander. but this is probably not practical.

You would need to provide the two functions described here.

Also here for another expander.

from sdfat.

Thanks! I have an ESP32 and connected is an Adafruit 3.5 TFT w/ capacitive touch w/ onboard SD slot.
I already use multiple port expanders for other purposes, so my solution uses a little single gate inverter (NOT-Gate) to select the lcd if the pin is low, and select the SD if high.
I will try to define my own functions and will come back if it works.

from sdfat.

my solution uses a little single gate inverter (NOT-Gate) to select the lcd if the pin is low, and select the SD if high.

It won't work. CS needs to be toggled in many places in the SD driver and is not just low when the driver is active. CS must not go low at random times since this may change the state of the SD.

It may sort of work but you will see instability.

SPI mode for SD cards barely works since the cards are designed for SD mode which is a very different protocol.

Here is one of the strange requirements for SPI on SD cards. It assumes no other device is active even though CS is high.

from sdfat.