@code7 as @Stephen6309 says, RRF 3.4.0 supports and external SD card (not USB drive) on the 6HC. If you run the 6HC with an attached Raspberry Pi then you can add USB storage to the Pi and print from it if you wish.
@siam
I've ran the this command and when the probe touches the bed the z reads out at -14. How do you recommend setting this current height to Z=0 permanently until I run the Auto Set Bed Height macro again? What can I send before sending M500 P31 which I have used in the past? I calibrate often to different bed heights depending upon the substrate I am printing on.