The next generation of cosmic and gamma ray experiments plans to answer persisting fundamental questions in ultra-high-energy astroparticle physics: what sources and acceleration mechanisms can produce the most energetic particles ever measured, with energies greater than 10 EeV? Are there any photons produced in our galaxy at 10 PeV? A proposed measurement technique for next generation air-shower arrays is the layered water Cherenkov detector. The water volume is optically separated such that a majority of the electromagnetic component of the air shower will attenuate in the top part, while the bottom one measures mostly muons. Currently, at the Pierre Auger Observatory in Malargüe, Argentina, two prototypes are deployed and have been taking data for over 10 years. The calibrated signals from these detectors can be used to extract the muonic and electromagnetic signals on an event-by-event basis, allowing for a direct estimation of the muonic component and a muon-independent air-shower energy reconstruction. We present the calibration method and the next steps to assess the layered detectors' sensitivity towards a mass-composition measurement for an extremely large array, like the Global Cosmic Ray Observatory (GCOS), or measurements of ultra-high-energy gamma rays with the Probing Extreme PeVatron Sources (PEPS) experiment.