> NXP lists the PCIe controllers in the P50xx as PCIe 2.0/3.0

They list it as "2.0/3.0" in one place and as "1.1/2.0" in others (like fact sheet and product brief). I firmly believe that "3.0" is not correct.

> what has Aeon/Varisys implented?

Their press release linked to above clearly states "Gen2".

> does AMD's statement about v2 apply to v1?

I think v3 cards not working in v2 slots also won't work in v1 slots, and that v3 cards working in v2 slots not necessarily work in v1 slots.