Cosmological simulations are an essential tool for the interpretation of upcoming cosmological surveys, however developing mock observations and performing analysis at the scale of state-of-the art simulations is a challenging task. In this talk I will first discuss how such simulations can aid in the interpretation of modern cosmological datasets. I will then detail the creation of synthetic sky catalogs from Hardware/Hybrid Accelerated Cosmology Code
(HACC) simulations such as the cosmoDC2 catalog built for the LSST-DESC collaboration, with a particular focus on weak lensing observables. Finally I will discuss current and future developments in simulation post-processing and analysis.