I soldered a grove cable to the 38&39 connectors inside mine and it sticks out the end above the card slotr.
I wager many people use the card reader for logging and with an atom you only get the rear 1&2 pins which limit you to i2c if you want lots of sensors and not all the m5stack sensors are ei2c
they could make a i2c card reader too, then it coul be part of i2c chain,. although i2c is slow than spi and not work with standard sd library, so would have to be a custom chip controlling it and probably just for pushing data tto log plus extra functions for
•format card
•does file exist
•does folder exists
•make file
•make folder
•append to file
•move file to folder
•delete file or folder
•push current date and time to chip so all create-modified time accurate but not integrated rtc