Surprise! The iMac Pro has Upgradable RAM and SSD - The Mac Observer
I want to upgrade RAM - iMac Pro - iFixit
A-Tech 128GB (2 x 64GB) RAM Kit for Apple iMac Pro (2017) - DDR4 2666MHz PC4-21300 ECC LRDIMM 288-pin Memory Upgrade Kit at Amazon.com
How to Upgrade RAM on MacBook Pro, iMac & More | AVG
iMac Pro Teardown Highlights Modular RAM, CPU and SSD Along With Redesigned Internals - MacRumors
Apple iMac Pro Memory Upgrade Kits - OWC
Base model iMac Pro teardown sheds more light on its upgrade potential - 9to5Mac
A-Tech 64GB (4 x 16GB) RAM for Apple iMac Pro (2017) - DDR4 2666MHz PC4-21300 ECC RDIMM 288-pin Memory Upgrade Kit at Amazon.com
64.0GB OWC Memory Upgrade Kit for iMac Pro (2017 - Current) - ynzal.com
Install memory in an iMac - Apple Support
A-Tech 16GB (2x8GB) RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010 27 inch 4-Core, Mid 2011 21.5/27 inch), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
A-Tech 128GB (4 x 32GB) RAM for Apple iMac Pro (2017) - DDR4 2666MHz PC4-21300 ECC RDIMM 288-pin Memory Upgrade Kit at Amazon.com