Compatibility of WD Blue SN 550 in Dell Vostro 3480 in my bios its written as M.2 PCIe ssd
To check if SSD is compatible with computer/Laptop, you need to look for the hard disk interface type of motherboard.
I would suggest you to check the detailed motherboard specs of the motherboard/Laptop manufacturer.
This is what i got the message from manufacturer
Two (2280 Key-M and 2242 Key-B) - Does WD SN550 256 GB SUPPORT THIS