Conductive buffer layers for semiconductor die assemblies, and associated systems and methods are disclosed. In an embodiment, a semiconductor die assembly includes first and second semiconductor dies directly bonded to each other. The first semiconductor die includes a first copper pad and the second semiconductor die includes a second copper pad. The first and second copper pads form an interconnect between the first and second semiconductor dies, and the interconnect includes a conductive buffer material between the first and second copper pads, where the conductive buffer material includes aggregates of conductive particles. In some embodiments, the first and second copper pads are not conjoined but electrically connected to each other through the conductive buffer material. In some embodiments, the conductive buffer material is porous such that the aggregates of conductive particles can be compressed together in response to the pressure applied to the conductive buffer layer.