OWC 16GB (2 x 8GB) PC21300 DDR4 2666MHz SO-DIMMs Memory Compatible with Mac Mini 2018, iMac 2019 and up, and Compatible PCs (OWC2666DDR4S16P) at Amazon.com
Kingston 16GB DDR4 2666MHZ SODIMM at Amazon.com
Apple Memory Module 16GB DDR4 2400MHz SO-DIMM (2x8GB) - Apple