Booting from a USB Drive
 
  For systems without CD drive, the NixOS live CD can be booted from a USB
  stick. You can use the dd utility to write the image:
  dd if=path-to-image
  of=/dev/sdX. Be careful about specifying
  the correct drive; you can use the lsblk command to get a
  list of block devices.
  
   On macOS
   
$ diskutil list
[..]
/dev/diskN (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
[..]
$ diskutil unmountDisk diskN
Unmount of all volumes on diskN was successful
$ sudo dd if=nix.iso of=/dev/rdiskN
    Using the 'raw' rdiskN device instead of
    diskN completes in minutes instead of hours. After
    dd completes, a GUI dialog "The disk you inserted was
    not readable by this computer" will pop up, which can be ignored.
   
  
 
 
  The dd utility will write the image verbatim to the drive,
  making it the recommended option for both UEFI and non-UEFI installations.