  JOcean is correct that 3080 does not seem to support M.2 sata.  Dell has only validated M.2 NVMe ssd for this model. M.2 2230 solid-state drive PCIe 3 Gen x4 NVMe, Class 35 Up to 512 GB M.2 2280 solid-state drive PCIe 3 Gen x4 NVMe, Class 40 Up to 1 TB   PS.  While Dell has not validated an off-label use, users often try on their own.  Thus, without finding user verified proof of failure so far, you could still try M.2 sata in 3080, but be prepared that it may not work. otoh I find the following spec from 3070 tower so it is possible that M.2 sata may run in 3070 tower.  
My Optiplex 3060 supports an M.2 SATA SSD. Planning to use this M.2 SATA SSD in an Optiplex 3070 and Optiplex 3080. I know ordering specs don't show this as an option, but ordering specs do not show many other options which are indeed possible. So the question, has anybody done this?   Thanks in advance guys!  
My Optiplex 3060 supports M.2 SATA SSD. Does the 3070 and 3080 also support M.2 
SATA SSD?