It does appear to be true that games today are not optimized for NVMe.
The current state of NVMe drives is this - Moving from HDD to SSD is a huge difference. But moving from SSD to NVMe results in hardly any improvement. It's literally just 1 second better despite being MUCH faster.
HDD top out at just under 200MB/s
SSD tops out at just under 600MB/s
So ~3x faster makes a HUGE difference in game loading.
But then after jumping up to an NVMe ( which in the above video tops out at around 3000MB/s .... it only loads games 1 second faster.
But then you can jump up again from NVMe (PCIe 3.0) to NVMe (PCIe 4.0) when read/write are in the 5000MB/s range currently.... pretty much no improvement again.
So, there it is.
I'm not sure why faster NVMe drives don't result in improved load times. Maybe the transfer speed simply isn't what's bottle-necking the loading past a certain point. Maybe games just need to be "optimized" for NVMe, whatever that means.
Maybe NVMe drives are better for streaming in data while playing open world games. I'm not sure if that's true today though.
But we are getting to the point that NVMe prices are getting really close to SSD prices, making far more sense to go NVMe ( even the cheap ones are 3x faster than the fastest SSDs ), even if they don't currently offer much benefit to gaming.... currently.