Ruddlesden–Popper nickelates provide a new route to high-temperature superconductivity, but the roles of the dx2−y2 and dz2 orbitals remain unresolved. In this talk, I focus on bilayer (La,Pr)3Ni2O7, where direct spectroscopic access to the superconducting phase has been a key challenge. By stabilizing superconducting thin films with a protective capping layer, we enable X-ray absorption and resonant inelastic X-ray scattering measurements across insulating, superconducting, and metallic regimes. We show that the in-plane dx2−y2 states form an itinerant backbone, while superconductivity emerges only when coherent dz2–pz–dz2 interlayer hybridization develops, accompanied by suppressed static spin order, and strongly damped spin excitations. Oxygen stoichiometry and epitaxial strain tune this interlayer channel, placing superconductivity within a narrow window of interlayer coherence. These results point to a multiorbital mechanism in which superconductivity arises from the interplay between an itinerant in-plane channel and an emergent interlayer coupling.