NVMe Drive in a MacBook Pro
It turns out that putting an NVMe drive into a MacBook Pro to replace the proprietary Apple blade is possible these days. Since macOS High Sierra, NVMe support has been officially included with the IONVMeFamily kernel extension and v10.13 also updated the EFI firmware of most of Apple’s current systems to include boot support for these drives. Thank you very much, Apple!
That doesn’t mean you can just fling an NVMe SSD in to replace your standard drive, though. You do need an adapter, but luckily these are relatively inexpensive. I plumped for this Sintech one because it mentioned Samsung 950 PRO support. It’s simply a physical converter; there are no electronics on it of any kind, which I thought was pretty interesting. It would appear that the socket on the logic board is simply a miniaturised PCIe expansion slot. The proprietary Apple SSD (manufactured by Samsung in all of the cases I’ve seen) actually shows itself as a SATA device on the PCI bus, so there must be some SATA conversion happening on the blade itself, because that’s not how the Samsung 970 EVO blade shows up. I’ll get to that in a tick.