You can swap out the OEM m2 drive with another M2 pcie nvme drive.  If you want more than 1 M2 drive, you can add it via adapter, or install it in the M2 slot, and wipe the 128GB drive and drop it into an adapter as a storage drive.  Adapters run around $10 so it may be a good way to extend the life of the OEM drive (use it as storage). 
Greetings.Firstly, I'm interested in upgrading the SSD on my R8, and I'm curious if I can swap out the SK Hynix SC311 128GB that came with my system, with a Sabrent 1TB , or would I have to get an adapter and install it in one of the slots below the GPU? This is my first time dealing with an SSD. Secondly, Crucial states that their P5 2TB is a suitable upgrade for the SSD currently installed in my system. Perhaps I'm mistaken, but having read various forum posts here, I was under the impression the max size for that slot was 1TB? Is this not the case? Thirdly, I'd like to do a fresh install of Windows 10 on this new drive. Would I download the USB thing from Microsoft, install the SDD into the computer, and then boot off the USB? Or do I need to contact Dell for a W10 copy/key, since I purchased the computer through them? Thanks for your time.
Aurora R8, SSD Upgrade Question