$ dongle-flash loopback.hex packaging iHex using nrfutil ... Error: No such file or directory (os error 2)
this indicates that
nrfutil, the Python tool, is not installed or not available in your PATH. Instructions on how to install
nrfutil can be found in the setup page and in the top-level README of this repository. If you install
nrfutil in a virtual environment you'll need to activate the environment; the
nrfutil binary must be available in your PATH.