For instance, the Intel 905p Optane.
Goes in a PCIe slot, hugely fast.
But at $1200 for 1TB, hugely expensive
https://www.intel.com/content/www/u...tane-ssd-9-series/optane-ssd-905p-series.html
Buy Intel Optane SSD 905P Series (960GB) (AIC PCIe x 4 3D XPoint): Internal Solid State Drives - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com
A Samsung 970 EVO in a PCIe adapter, in the proper system, would also see its full native speed.
Slower than that 905p, but much much less expensive per GB.
In a native M.2 port on a relevant motherboard, it would also see its full native speed. No 'adapter' needed.