Amazon.com: PCIe NVMe Gen3x4 SSD 1TB 512GB 256GB 128GB 3D TLC NAND Flash Hard Drive SSD Replacement for MacBook Air 2013-2017, MacBook Pro Retina 2013-2015, iMac 2013-2017, Mac Pro 2013, Mac Mini 2014 (1TB) : Electronics
Amazon.com: OWC 2TB Aura Pro X2 NVMe SSD Upgrade Kit Compatible with Select 27" and 21.5" iMac Models (Late 2013 - Current) : Electronics
How to Install/Upgrade the PCIe SSD in a 27-inch iMac (2019) iMac19,1 - YouTube
Apple Proprietary SSDs: Ultimate Guide to Specs & Upgrades | BeetsBlog
How to Install/Upgrade the PCIe SSD in a 27-inch iMac (2019) on Vimeo
Timetec 256GB MAC SSD NVMe PCIe Gen3x4 3D NAND TLC Read Up to 1,950MB/s Compatible with Apple MacBook Air (2013-2015, 2017), MacBook Pro (2013-2015), iMac (2013-2019), Mac Pro (2013), Mac Mini (2014) at Amazon.com
Upgrading a 27-inch iMac 5K to 14 terabytes - Replacing the Fusion Drive with both a SSD and an harddisk
Upgrading an older iMac's PCIe SSD: Third-party solutions that save you beaucoup bucks | Macworld
128GB FUSION DRIVE PCIe SSD Apple iMac 21.5" A1418,27" A1419 Late 2013,2014,2015 | eBay
SOLVED: Is it possible to upgrade the PCIe SSD? - iMac Intel 27" EMC 2639 - iFixit