Intense electromagnetic fields from ultrarelativistic heavy ions can trigger photonuclear reactions, which are used to probe the nuclear gluon distribution and gluonic fluctuations over a large range of Bjorken-$x$. Our study examines ultra-peripheral and nuclear-overlap collisions, reporting on the photoproduction of J/$\psi$ in peripheral Pb$-$Pb collision. In particular, the rapidity-dependence of the measured cross section and the measured polarization. We present new Run~2 measurements, including spectra of incoherent J/$\psi$ in Pb$-$Pb UPCs at both forward and midrapidity, revealing the substructure of the lead nucleus. Additionally, we observe J/$\psi$ photoproduction with proton dissociation in p$-$Pb collisions, offering fresh insights into proton sub-nucleonic fluctuations. Combining forward and midrapidity data offers a robust test of theoretical models.