Surprise! The iMac Pro has Upgradable RAM and SSD - The Mac Observer
OWC SSD Upgrade Kits for 21.5-Inch iMac (2013 - 2019)
iMac Intel 21.5" and 27" (Mid 2011) SSD Upgrade Bundle - iFixit Store
OWC DIY Drive Upgrade/Install Kits for Apple iMac Models
How To Upgrade Your iMac with an SSD (2021 updated) | Upgradeable Australia
2011 imac 27" 32GB - final stage of 1TB + 2TB SSD upgrade (replaced HDD & optic drive). Also cleaned out the fans and case. Running 'SSD Fan Control' & 'Macs Fan
iMac SSD Upgrade with 1TB Samsung 860 EVO - YouTube