I have several SATA III SSDs and one nvme m.2 SSD in my current PC.
The SATA III SSD's are 3x Crucial MX500 500GB SSDs, 1 Crucial MX500 1 TB SSD and 1x Crucial MX500 m.2 SATA II SSD and 3 HDDs that I use for backing up data.
My m.2 nvme SSD is a Samsung 970 EVO 500 GB SSD (as my boot/windows10 drive).
I just bought the 970 EVO in October.
While I don't regret the purchase, I can say that it really has not made a noticeable difference in everyday performance.
So IMO, if you are happy with the performance of your PC with a conventional 2.5" SSD (like the 860 EVO), there is no real world benefit to buying an nvme SSD to replace it.