*******************************************************************************************
build_flags = 
	-DARDUINO_USB_CDC_ON_BOOT=1
	-DARDUINO_USB_MODE=1
This activates Hardware CDC and changes the behavior of the Serial objects:
Serial: output is routed to the builtin USB Serial
Serial0: output is routed to UART0 (RX: 20 / TX:21)
Serial1: output is routed to UART1 (RX: 18 / TX:19)
*******************************************************************************************

ESP32S3 pins:
https://github.com/atomic14/esp32-s3-pinouts
https://www.atomic14.com/2023/11/21/esp32-s3-pins.html
*******************************************************************************************

another S3 variant with PSRAM:
https://community.platformio.org/t/support-to-cunfigure-luatos-esp32-s3/39257/10
*******************************************************************************************