The Linux kernel has been updated for some new hardware that still includes the AMD Van Gogh APU, which is currently only used in the Steam Deck. Popular speculation is that Valve will release an updated Steam Deck, one that still uses the same APU (so same performance), but had other changes to the hardware. Possibly different screen, larger battery, etc.
Possible code name for the hardware is Galileo.
If you want more/better info, I’d recommend reading the linked article.
No, foveated rendering doesn’t need the game to support it I use it all the time