nrfutil device uses the same architecture and programming methods as the nRF Connect for Desktop Programmer app for listing, programming, and other device operations.
All programming operations are exposed through nrfutil device program. The command is the same regardless of whether the programming is over SEGGER J-Link, MCUBoot serial recovery, nRF9160 modem upgrade, or other. nRF Util automatically selects programming method based on the device traits and the firmware file format.