This project aims at exploiting the scientific projects awarded to Belgian astronomers as a result of obtaining a considerable amount of JWST/MIRI Guaranteed Time Observations, Early Release Science data and open- time Cycle 1 and 2 observations. In this PRODEX project at Ghent University, we will focus on one key JWST science topic: (extra-)galactic science, and by exploiting the expertise and synergies of the other two partner institutes (ULiège and KULeuven). Using JWST/MIRI (extra-)galactic observations we will study dust processing in nearby galaxies, active galactic nuclei (AGN) and the specific environments of the circumgalactic medium in NGC891 and the Galactic supernova remnant Cassiopeia A.