Through imaging and spectroscopy, modern astronomical surveys have dramatically improved our understanding of large-scale structure formation and astrophysics over cosmic history. SPHEREx, NASA’s most recent MIDEX mission, began survey operations on May 1st, 2025 and will deliver the first all-sky, low-resolution spectrophotometric survey in the near-infrared (NIR) spanning 0.75 - 5.0 um, enabling novel science investigations in inflationary cosmology, galaxy formation and evolution, Galactic ices, and more. In this talk, I will introduce the SPHEREx mission, describing the current survey status and science data modeling required to deliver the largest galaxy redshift catalog (by volume) to date. After highlighting progress and challenges ahead for cosmology with SPHEREx – which will probe primordial non-Gaussianities and baryonic oscillations – I will turn focus to SPHEREx’s unique diffuse mapping capabilities, which will enable a detailed characterization of the NIR extragalactic background light with unprecedented sensitivity. In this portion of the talk I will highlight recent pathfinder measurements from the Cosmic Infrared Background ExpeRiment (CIBER) and discuss more general implications for NIR intensity mapping as a complementary probe of large-scale structure and astrophysics.