From what I understand based on some articles and videos I saw explaining it (I'm a mechanical engineer, not a computer engineer, so a lot of it is over my head), the ability to take advantage of the better SSD is something that would be built into the engine. So Epic could build Unreal Engine 5 to take advantage of it and the developers wouldn't have to do that themselves. And from what I understand, the data stream to the cpu will be through PCIe4 going through a northbridge (or whatever they will call the memory controller on the PS5) and so should work just like on a PC. Which would mean that devs won't need to do anything special to take advantage of the new drive technology. So those "elevator loading screens" for example would be able to be basically instantaneous instead of a few seconds, based on what Sony is saying anyway. But, the big impact that Sony claims this will have on games is for open world games as they'll be able to stream data off the SSD with such speed that environmental assets will be able to be loaded straight from the drive and so draw distances will be longer, environments will be be more diverse, and worlds will be more populated. Again, this is all based off what Sony has said about it and what people who know way more about computers than me have managed to dumb down into layman's terms (sort of, I do understand computer architecture more than the average person, but not enough to fully most of what I've seen about it)
Also, by the end of the PS3's life cycle, the cell processor absolutely was showing how powerful it was. But it was only on first party games and only after Naughty Dog figured out how to fully take advantage of it.
