The Inspiron 3583 can accept a M.2 NVMe SSD. I know because I have the same exact model and I've installed a NVMe as my boot drive. The M.2 drive can be seen in the BIOS screenshot that the OP has posted. As for upgrading storage, the OP should keep the NVMe SSD as the boot drive and add a 2.5" SSD for additional storage, that is, if the OP doesn't want to copy the existing NVMe to another NVMe of a larger capacity, or reinstall Windows and apps on the new NVMe. The downside is that the total storage will not be split across the two drives, and files would have to manually be saved or moved to the second drive. Personally, I would purchase a M.2 NVMe-to-USB adapter, install the new NVMe drive in it, connect it to the computer and use Macrinum Reflect to copy the partitions from the existing NVMe to the new one, then shut down the computer, switch the NVMe drives around and boot. Or...should the OP want to install a fresh install of Windows on the new NVMe, the adapter can be used to copy over existing files from the old NVMe.
I've watched You Tube but am still so confused.  First, I have no idea which hard drive I have now. All I know is it's not nearly enough room for what I need, so I'm quadupaling it. Second, do I replace or add, or do I even have the option. I don't want to lose all my data.  The installation part I think I've got, but my question is, if I am adding a 1TB SSD Crucial hard drive (the thin kind, not the box), do I need to clone my existing hard drive or will it all still be there since I'm adding, not replacing? If so, do I need a special cord or USB attachment? What if I have everything backed up to a recovery drive (USB) and on the cloud? Please explain this to me like I'm a 5 year old. LOL. Also adding 8GB ram to make 16 total. This is what I purchased. Crucial 8GB Single DDR4 2666 MT/s (PC4-21300) SR X8 SODIMM 260-Pin Memory - CT8G4SFS8266 Thanks in advance. Ally
Help with adding SSD and RAM on 3583 laptop