  Motivated by the capability of the KATRIN experiment to explore the existence
of KeV neutrinos in the $[1-18.5]$ KeV mass range, we explore the viability of
minimal extensions of the Standard Model involving sterile neutrinos (namely
the 3 + $N$ frameworks) and study their possible impact in both the beta energy
spectrum and the neutrinoless double beta decay effective mass, for the two
possible ordering cases for the light neutrino spectrum. We also explore how
both observables can discriminate between motivated low-scale seesaw
realizations involving KeV sterile neutrinos. Our study concerns the prospect
of a Type-I seesaw with two right-handed neutrinos, and a combination of the
inverse and the linear seesaws where the Standard Model is minimally extended
by two quasi-degenerate sterile fermions. We also discuss the possibility of
exploring the latter case searching for double-kinks in KATRIN.
