Both the GPU and CPU are likely to be fairly vanilla AMD parts. There isn't much in standard PCs that can be left out, and it seems pointless for AMD to develop major functionality that they wouldn't also included in their PCs parts.
The days of heavily customised console hardware are over, now it's about smart ways to wire together standard PC parts to maximise value for money.
This isnt something "heavily customised", its like takeing part of Zen 3 (which should be releaseing this year), and useing it on a zen2 cpu, with slight modifications.
Its not something brand new developed just for sony.
AMD is constantly working on makeing their cpu's better, so when they make advancements, takeing something new and putting it into something old, often probably doesnt take too much work. The cost in R&D are near zero, since its something they already worked out long ago for a future product.
Sounds like it is more expensive then.
Honestly dont think so. Probably not a huge price attachted to this sort of thing.
Necro-bump this 2020: http://gamrconnect.vgchartz.com/thread.php?id=229249
Bumb in 2021: http://gamrconnect.vgchartz.com/post.php?id=9047071