The Dell WiFi M.2 socket is specifically designed for wireless only and would not work with M.2 ssd.  It is not connected to PCIe lane of motherboard.  WiFi M.2 slot may also be keyed differently so that M.2 ssd would not fit.
I see the motherboard have 1 x 2230 slot (use by the WiFi) and 1 x 2280 (use by the M2 Nmve SSD).  Can I remove the Wifi card and use an 2230 Nmve SSD instead ? (I did not need the Wifi). 
G5 M2 2230 wifi replace by an M2 2230 SSD ?