OWC 32GB (2 x 16GB) PC21300 DDR4 2666MHz SO-DIMMs Memory, Compatible with Mac Mini 2018, iMac 2019 and up, and Compatible PCs, (OWC2666DDR4S32P) at Amazon.com
HyperX Fury 16GB DDR4 2666MHz DRAM - Newegg.com
Kingston 16GB DDR4 2666Mhz ECC Unbuffered Server Memory - KTL-TN426E/16G - Server Memory - CDW.com