Apple iMac 21.5 A1418 27" A1419 128GB SSD Hard Drive (Late 2013) 2014 2015 2017 | eBay
Amazon.com: Sintech M.2 nVME SSD Adapter Card Upgrade Kits,Compatible for MacBook Air(2013-2017 Year) and MacBook PRO(Late 2013-2015 Year,iMac : Electronics
661-07315) 256GB NVMe SSD - iMac 27″ A1419 (2017)
Timetec 256GB MAC SSD NVMe PCIe Gen3x4 3D NAND TLC Internal SSD Compatible with Apple MacBook Air (2013-2015, 2017), MacBook Pro (2013-2015), iMac (2013-2019), Mac Pro (2013), Mac Mini (2014) - Walmart.com
Teardown of New iMac Reveals Replaceable CPU, RAM | PCMag
Timetec 256GB MAC SSD NVMe PCIe Gen3x4 3D NAND TLC Internal SSD Compatible with Apple MacBook Air (2013-2015, 2017), MacBook Pro (2013-2015), iMac (2013-2019), Mac Pro (2013), Mac Mini (2014) - Walmart.com
Genuine Apple 2TB NVMe SSD MZ-KKW2T00/0A6 655-1996B for Mac Pro 2013 & iMac 2017 | eBay
Upgrade your iMac with OWC, 2017 4K Retina Edition
2017 21.5" inch iMac A1418 SSD Hard Drive Replacement Upgrade Screen Removal - YouTube
Base model iMac Pro teardown sheds more light on its upgrade potential - 9to5Mac
SSD Upgrades for Apple iMac 27-Inch Late 2013 - 2019
661-02291 Apple Logic Board 2.3 GHz SSD for iMac 21.5" 2K 2017 A1418