This is an old Phoenix legacy bios and specific Dell, not possible using modern/regular know methods.
Stick with a good/fast 2.5" SSD or an SSD RAID0 if possible.
You may try to venture with this [Experimental] NVMe Option ROM - BIOS/UEFI Modding / BIOS modules (PCI ROM, EFI and others) - Win-Raid Forum (level1techs.com) with a huge chance of fail/bricked system board…
Or maybe Clover method: NVMe Support for old Systems - Win-Raid Forum
My opinion only, you should wait for other users pov.