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
Apple Memory Module 32GB DDR4 2666MHz SO-DIMMS (2x16GB) - Apple
QNAP 32GB DDR4 2666 MHz ECC SO-DIMM Memory
32GB (2x16GB) DDR4-2666MHz PC4-21300 1.2V SODIMM Laptop Memory by NEMIX RAM at Amazon.com