Since the discovery of the first radio pulsar fifty years ago, the population of isolated neutron stars (INSs) in our Galaxy has grown to 2800, out of which a few percent are exclusively seen in X-rays. Despite their scarcity, the X-ray emitting INSs are the key to understanding aspects of neutron star phenomenology and evolution not observed in normal pulsars. eRASS will unveil the X-ray faint end of the population; therefore, it has the unique potential to constrain evolutionary models and advance the understanding of the NS population as a whole.