SD Card support is nothing new to Marlin, of which Swordfish is based.
Getting it optimised to work with CNC machines is a different ball game.
Work is currently under way to get SD card support flawlessly working between Swordfish and Gladius, enabling play and walk away machining operations.
It is already supported on our machines, however there is a process to go through before you can utilise it - nothing major but more of a pain than anything else.
[You have to put the files you wish to CNC on the SD card by a PC first]
M20 - List SD Card; List all the files on the SD card
M21 - Init SD Card; initialise the SD card
M23 - Select SD File; for example in the below image, M23 P4TEST~1.GCO
M24 - Start SD file