Microelectronic assemblies, related devices and methods, are disclosed herein. In some embodiments, a microelectronic assembly may include a first die having a surface; a template structure having a first surface and an opposing second surface, wherein the first surface of the template structure is coupled to the surface of the first die, and wherein the template structure includes a cavity at the first surface and a through-template opening extending from a top surface of the cavity to the second surface of the template structure; and a second die within the cavity of the template structure and electrically coupled to the surface of the first die by interconnects having a pitch of less than 10 microns between adjacent interconnects.