Even these lower-end NVMe drives tend to have rather good read performance, up to several times that of a SATA SSD for sequential transfers, although in terms of real-world application and game loading performance, the difference is generally more like 10%, due to the system waiting on processing data much of the time. That might change in future games designed with fast SSD asset streaming in mind though, which is something the next consoles will apparently be focusing on.
Some like a 970 Evo will be faster still, but again, since the system is waiting on other things much of the time, you are unlikely to see much of that additional read performance for the time being, at least for anything other than tasks like copying large files.
Those higher-end SSDs do offer some benefits though. If one is constantly performing a large amount of file writes to the drive, their higher write endurance could allow the drive to last longer. Many of the lower-end drives will also use QLC flash, which is slower to write to, but they dedicate a portion of that to be used as a fast SLC cache, which keeps write performance high under most common usage scenarios. If one is quickly writing many gigabytes of data to the drive within a short span of time though, it's possible to see a significant slowdown in performance until the cache can clear, though again, that write cache is typically many gigabytes in size, so it's not a problem in most scenarios.