If upgrading storage in the ~1TB neighborhood, I'd just replace the stock NVME with a 1TB drive and reinstall Windows. Windows key should be stored in the firmware for a modern UEFI system and you can sock drawer the OEM drive to put back in if you sell or gift the system down the road.
Here's a TLC NVME 1TB for $100 USD. Not going to be as fast as a 970 EVO, but will still run circles around a SATA drive, plus it gives you the option of one large volume vs managing storage across C and D drives.
https://www.amazon.com/Silicon-Power...1&s=pc&sr=1-13
Edit: Adding link to media creation tool to generate a bootable USB to install current Windows 10 build if you replace stock drive.
https://www.microsoft.com/en-us/soft...load/windows10