Dual Storage On Thinkpad T480: SSD On WWAN Slot (New Version) 

yes you can as you can see on the video (e.g. 128 GB WWAN SSD identified as C: drive meaning the windows ran on it). On the other hand, I put HDD on 2,5 in storage slot used exclusively for storage.

@@insidelook8588 Thanks so much, I can set the boot order in BIOS, right? I mean i may always change the boot drive.

@@dannyyau7295 sure you can. If we put OS on both SSD, we can choose the boot drive priority via BIOS if we want to start with certain drive #edited.