The bound on the sum of neutrino masses from various cosmological surveys is becoming increasingly stringent, and is now in significant tension with constraints from neutrino oscillation data and terrestrial experiments probing the absolute neutrino mass scale. In the first part, I will discuss extended dark sectors and their phenomenology. In the second part, I will introduce several non standard cosmology scenarios collectively referred to as large neutrino mass cosmologies that allow for relaxing the bound from cosmology and reconcile it with the ones from laboratory, emphasizing the role of an enlarged dark sector. In this framework, the dark sector thermalizes with Standard Model neutrinos after neutrino decoupling but before recombination, via a dark U(1) gauge interaction. This late equilibration suppresses the abundance of active neutrinos, thereby allowing sizable neutrino masses to remain consistent with cosmological observations.