  The magnetotransport in phase-separated (Ga,Fe)N containing
$\gamma$'-Ga$_y$Fe$_{4-y}$N (0\,$<$\,y\,$<$1) nanocrystals (NCs) is studied in
the temperature range between 2\,K and 300\,K. The evolution of the resistivity
and of the magnetoresistance (MR) as a function of temperature points at two
conduction mechanisms: namely a conventional Arrhenius-type one down to 50\,K,
and Mott variable range hopping at lower temperatures, where the spin-polarized
current is transported between NCs in a regime in which phonon-scattering
effects are not dominant. Below 25\,K, the MR shows a hysteretic contribution
at magnetic fields $<$1\,T and proportional to the coercive field. Anisotropic
magnetoresistance with values one order of magnitude greater than those
previously reported for $\gamma$'-Fe$_4$N thin films over the whole considered
temperature range, confirms that the observed MR in these layers is determined
by the embedded nanocrystals.
