I have been backing up my hard drive by making a 'clone copy' and setting it aside. I've tested those and you can literally plug them in (SATA, or via SATA-to-USB connector) and they boot the system, no different than the original.
Question....if I backed up a 750-series PCIe add-in card onto a regular SATA SSD (I would easily do it via a Apricorn SATA-to-USB connector), would I be able to boot the system with the regular SSD?
Booting from NVMe* drives require specific configuration, like NVMe* drivers, BIOS in uEFI mode and GPT partitions. This configuration may not be compatible once you try to boot from the SATA device, so we cannot guarantee that this would work.