The ExaSky ECP effort is a comprehensive program using the HACC and Nyx codes for cosmological simulations. The extreme-scale framework, HACC, is designed for high performance, scalability, and the ability to run on all supercomputing platforms. The Eulerian AMR code Nyx complements the Lagrangian nature of HACC; the two codes are part of a joint science program. The purpose of the effort on JLSE resources is to ready the codes for Aurora, select appropriate programming models, and to optimize code performance.