nvmefwupdater is a tool used by Apple to update the NAND firmware.
"NVMe (non-volatile memory express) is a host controller interface and storage protocol created to accelerate the transfer of data between enterprise and client systems and solid-state drives (SSDs) over a computer's high-speed Peripheral Component Interconnect Express (PCIe) bus." - [[source]https://searchstorage.techtarget.com/definition/NVMe-non-volatile-memory-express]
The NVMe firmware updater talks to the AppleEmbeddedNVMeController kext. It will attempt to put the NAND in BFH mode