If you’re practicing 3-2-1 backups then you probably don’t need to bother with RAID.
I can hear the mechanical keyboards clacking; Hear me out: If you’re not committed to a regular backup strategy, RAID can be a good way to protect yourself against a sudden hard drive failure, at which point you can do an “oh shit” backup and reconsider your life choices. RAID does nothing else beyond that. If your data gets corrupted, the wrong bits will happily be synced to the mirror drives. If you get ransomwared, congratulations you now have two copies of your inaccessible encrypted data.
Skip the RAID and set up backups. It can be as simple as an external drive that you plug in once a week and run rsync, or you can pay for a service like backblaze that has a client to handle things, or you can set up a NAS that receives a nightly backup from your PC and then pushes a copy up to something like B2 or S3 glacier.
The other poster said it’s about convenience but that’s not really true. The claim to fame for NVMe drives is speed: While SATA SSDs can theoretically run at up to 500 MB/s, the latest NVMe drives can hit 7000+ MB/s.
It’s for this reason that you should pay attention to which NVMe drive you choose (if speed is what you’re after). SATA-based M.2 drives exist – and they run at SATA speeds – so if you see a cheap M.2 drive for sale it’s probably SATA and intended for bulk storage on laptops and SFF PCs without room for 2.5" drives. Double check the specs to be sure what you’re getting.