Answer to "Upgrading from 2TB Fusion Drive to NVMe/SSD Blade/PCIe SSD/M.2"These are easy to get to. You use a tool that looks and feels exactly like a guitar pick (and is readily available at any music store) to separate the screen from the case. You'll need the right double-stick foam tape to put it back together. iFixIt and OWC have tutorials. OWC has the right tape and a tool that looks like a plastic pizza wheel — faster than the guitar pick. Now that 2T SSDs are under $300 and a 2T blade can be had for around $700, it's an upgrade that makes sense. Getting rid of that mechanical HHD lets your iMac run a lot cooler, too — the energy savings will pay for itself over time. If you can find an Apple system pull, that's best for the blade. 1T are easy to find; 2T don't come up all that often and are expensive—an m2 with an adapter is 2x that of an SATA SSD but not nearly as fast as the Apple NVMe PCIe quad blade as found in the 2017 iMac and certain MacBook Pros. APFS does not run on fusion drives—even when it's a blade fused to an SSD.