The European Spallation Source (ESS), currently under development in Lund, Sweden, will provide a high-intensity pulsed neutrino beam, offering unprecedented opportunities for a high-statistics measurement of Coherent Elastic Neutrino-Nucleus Scattering (CE \(\nu \) NS) with state-of-the-art detection technologies. The ESS facility will allow for a precise determination of Standard Model (SM) parameters and also offer enhanced sensitivity to beyond-the-Standard Model (BSM) physics compared to current experiments. In this work, we investigate interesting upscattering channels involving massive Sterile Neutral Leptons (SNLs) and their detection prospects at the upcoming ESS CE \(\nu \) NS experiment. We consider two scenarios: (a) SNL production via upscattering of active neutrinos on nuclei through the sterile dipole portal, and (b) upscattering mediated by Lorentz-invariant operators—scalar, pseudoscalar, vector, axial-vector, and tensor—collectively referred to as Neutrino Generalized Interactions (NGIs). For both cases, we highlight the complementarity of the future ESS sensitivity with existing experimental and astrophysical constraints, noting that the ESS can provide superior limits in certain regions of parameter space.