Hi there,
SO let’s keep it in one thread so we don’t have to jump around.
The strapping pins are important when needing certain options at boot time.
Refer to the technical reference guide for the ESP32S3 NO they do not use the Peripheral multiplexor so they can’t be reassigned. They are however latched at boot time so you can use them as pins after that. (most people and designs stay away from that)
As indicated in the other thread, Look at the schematic, it and the pins xls spreadsheet are on the resources section of the wiki, READ it, come back ask more good questions LOL 
