Taking notes.
I can see the SD card on a ESP32-CAM finally! I read conflicting information about the settings. I have not tried to serve the gcode yet.
In esp3d/configuration.h I changed;
-#define SD_DEVICE_CONNECTION ESP_DIRECT_SD
-#define SD_DEVICE ESP_SDIO
That is it. My SD card is formatted fat32.
P.S. Found this cool esp32-cam site during my travels, 60+ ESP32-CAM Projects, Tutorials and Guides with Arduino IDE | Random Nerd Tutorials