Set de pin number to -1
As you can see in esp_lcd_panel_rgb.c there is this if inside lcd_rgb_panel_configure_gpio
if (panel_config->de_gpio_num < 0) {
// Hsync and Vsync are required in HV mode
valid_gpio = valid_gpio && (panel_config->hsync_gpio_num >= 0) && (panel_config->vsync_gpio_num >= 0);
}
You can trace it further from there to see how it is configured inside the library (component)
It worked on me both with sync and de up to 800x480 with lvgl
I have used this devboard https://www.aliexpress.com/item/1005004952694042.html (https://www.aliexpress.com/item/1005004952694042.html)
I didn't like that usb pins that can be used for jtag are used in capacitive IC
Recently I found and an other board that if I remembered correctly usb pins are free
https://www.makerfabs.com/esp32-s3-parallel-tft-with-touch-7-inch.html (https://www.makerfabs.com/esp32-s3-parallel-tft-with-touch-7-inch.html)