Is it really worth those $23 though? The following Linus video shows there's very little difference between gen5 and gen4 and I'm guessing it's similar results between gen4 and gen3 as well. I'd probably prefer to get the cheaper drive and then pick up a delicious $23 meal vs the better SSD honestly. Heck, I'm still using my SATA SSD when my new MOBO I got in 2020 has an m.2 slot (I think 2 of them).
And one comparing SATA to NVMe SSDs:
Right now you might be correct, especially for something like playing video games. Thinking toward the future though, Microsoft is going to be coming out with DirectStorage, where SSDs will be able to bypass the CPU and load data directly onto a graphics cards, and in that the faster speed of a gen 4 or gen 5 drive will probably have substantially better performance compared to gen 3. The PS5 has similar architecture to reduce load times, and it doesn't even work with gen 3 drives.
Also, if you're building a new PC and planning on copying a lot of data from your old PC onto it then your definitely going to see a pretty big difference in the performance in that case. That's not a massive selling point though unless you plan on copying a lot of data very often.
I mean, if you're just looking at it purely from the perspective of "will this give me a substantial gaming performance uplift right now?" why even go with M.2? You could just use a sata SSD and end up with similar gaming performance for even cheaper.
Some people will pay $100 more for a PC component to get 10% more speed, so from that perspective getting 100% more speed and some future proofing for $23 seems like a pretty good deal.