Need your info for the following.
1. Why 1 TB of HDD and combine with 4 TB SSD, maybe can consider to work without HDD.
2.. How you determine your current NVME is crappy?
3. For boot drive, you will never be abled to get full 100% capacity due to some UEFI and hidden partition for recovery.
Please provide your full spec of your system as detail as possible and usage of your system for current forums members here assist you. Thank you.