Where are elements heavier than iron (Fe) primarily manufactured, given core fusion's energetic limitations?

In the extreme conditions surrounding a supernova explosion or late-stage evolution of specific stars

Core fusion ceases to be a viable energy source once the stellar core is dominated by iron because fusing iron is energetically unfavorable (endothermic). Consequently, elements heavier than iron cannot be built through standard core burning. Their creation requires environments providing immense energy and a large supply of free neutrons. These conditions are met during the extraordinarily energetic events associated with the death of massive stars, specifically the shockwave and neutron flux surrounding a supernova explosion, or during specific late evolutionary stages like the s-process in AGB stars, which contribute to the overall inventory of heavy isotopes.