the BSP controls how the pins are mapped… what physical pin goes to which gpio… each XIAO model had a different mapping scheme… the BSP works in the background to do this mapping… so for example if you use pin D7 with the board support package loaded for a XIAO ESP32s3 instead of an Esp32C3 all betts are off… D7 is not a real pin… it is a representation of a location on the board and a “variable” for lack of a better word in the code. If you multiply axb=c you cannot expect to get the same answer if you multiply exf=g will never ever work excessivly high baudrate will cause the XIAO to not accept new code upload without hard boot-reset and can be a pain in the A… also fast or slow baud can effect waste of processor respurces and interupt problems