Hi there, and Welcome here
so from the IDF info I see this?
“Different from the API before ESP-IDF v4.0, the functionality of esp_flash_* APIs is not limited to the “main” SPI flash chip (the same SPI flash chip from which program runs). With different chip pointers, you can access external flash chips connected to not only SPI0/1 but also other SPI buses like SPI2.”
from this link, I wouldn’t think with Xiao that it’s possible , but you may try and see if it works
SPI Flash API - ESP32-S3 - — ESP-IDF Programming Guide v5.2.2 documentation.
HTH
GL 
PJ
