So - I've found that the WD SN770 simply is not compatible with the Precision 7550.  However, I was able to chat with Samsung directly and the 970 Evo Plus 2TB is now installed and working properly, in case anyone wanted to see the resolution.
Precision 7550 specs state up to 2TB M.2 NVMe supported (Class 40), but only up to 1TB M.2 NVMe (Class 50).  However, it doesn't appear anyone outside of Dell uses those terms.  How can I get my 7550 to detect the SN770, or is this simply too good a drive for my (only 2 year old) 7550?  What other M.2 2TB NVMe options WOULD work?  Thanks in advance for any help/guidance! (Note: Yes, the 7550 is PCIe 3.0 and the SN770 is PCIe 4.0, but should be downwards compatible so I can't see how that would be the issue.)
Precision 7550 BIOS not recognizing WD SN770 2TB NVMe SSD