I just picked up an SN850X 4TB with the intention to use it on a new X670E/7950X/7950XT build for a game drive to support DirectStorage and Smart Access Storage, however AMD has been cagey about details regarding Smart Access Storage support, only saying that "once we remove the platform bottlenecks some drives that relied on them don't perform so well relative to others" and that they would come out with a qualified vendor list of drives supported for Smart Access Storage.
The key here being Smart Access Storage is an AMD proprietary implementation that allegedly cuts out even more platform bottlenecks than traditional DirectStorage on just any old system with an NVME drive. I hope they share details soon, I suppose those details won't be until Zen 4 launch time or so at the end of the month, so.....
PCI-e 5.0 drives are supposed to start hitting around the same time, however I have only seen off the shelf designs using Phison controllers/etc. demonstrated. I refuse to use off the shelf designs because I want to support full stack custom designs, like the Samsung 980Pro/990Pro, SN850/850X, P41 Platinum, etc. as I firmly believe custom designs are better and also introduce more competition and diversity in the market offerings.
I don't expect any full stack custom designs for PCI-e 5.0 will debut anytime soon, unless somebody has a design ready to go and is waiting to demo/launch it later.