Yes, config-override.g serves exactly the same purpose as EEPROM does in 8-bit firmwares.
Both config.g and config-override.g contain only GCode commands. See https://duet3d.dozuki.com/Wiki/Gcode for the list.
The SD card file structure and the purpose of the files is documented at https://duet3d.dozuki.com/Wiki/Firmware_Overview#Section_SD_card_structure.
HTH David