Most would prefer any sort of SSD (NVME or SATA, depending on your system's age/capabilities) to any actual spinning drive, especially for the OS and most applications. (Systems with SSDs boot in as little 5-10 seconds compared to 20-30 with a spinning drive, closer to 40 seconds if a typical laptop spinning drive at 5400 rpm)
In any event, installing WIndows (make USB flash drive installer media from MS's Media creation tool ) to an SSD takes all of 5 minutes these days (vs. 15-20 minutes installing to a spinning drive). Gather all your needed chipset and graphics appropriate drivers ahead of time.
As your system was already Win10 activated, simply choose 'I don't have a key' at time of installation, and, during handshakes w/ MS later, it will reactivate automatically due to a unique hardware coding (like a model/serial number equivalent) stored at MS's vast databases.