Will be interesting to see what an eventual Deck 2 is capable of since AMD seems to be at the lower end of ray tracing efficiency compared to Nvidia (at least, from the outside looking in for someone with an RX 480...)
Do we know enough about the next gen Steam Deck to be able to make assumptions about what GPU brand might be used or whether Nvidia would still be ahead of AMD in this area?
Unless Valve can either find or pay a company that does a custom packaging of a Nvidia GPU with x86 (like the Intel Kaby Lake-G SoC with an in-package Radeon), very unlikely. The handheld size makes an “out of package” discrete GPU very difficult.
And making Nvidia themselves warm up to x86 is just unrealistic at this point. Even if e.g. Nintendo demanded, the entire gaming market — see AMD’s anemic recent 2024Q1 result from gaming vs. data center and AI — is unlikely to be compelling enough for Nvidia to be interested in x86 development, vs. continuing with their ARM-based Grace “superchip.”
Nvidia does not make x86 SoCs. Even if Valve goes with a separate Nvidia dGPU like in laptops, they would have to abandon their last 10+ years of Linux work, and goals of having a platform which isn't controlled by Microsoft.