You can just leave the SD code as is since the SDCS pin is available.
MMC mode does not use the SDCS pin so its possible you would get use of the LED back if you used that mode. There are examples of using the SD card in MMC mode on the Random Nerd Tutorials site;
https://randomnerdtutorials.com/esp32-cam-photo-microsd-card-timestamp/
You can try just shifting the display onto the other ESP32S3 SPI bus, this is a summary of the code, note the pins used are different to the ones shown in your schematic;
#define TFT_MISO 0
#define TFT_MOSI 1
#define TFT_SCLK 2
#define TFT_CS 3
#define TFT_DC 4
#define TFT_RST 5
SPIClass disp_SPI(HSPI);
Adafruit_ST7789 tft = Adafruit_ST7789(&disp_SPI, TFT_CS, TFT_DC, TFT_RST);
void setup() {
disp_SPI.begin(TFT_SCLK, TFT_MISO, TFT_MOSI, -1);
tft.init(240, 280);
Etc.
Note the TFT SPI bus is now on pins 0,1,2.