I think they’d have to port the game to OpenXR to do that? Considering they’re upgrading Steam Input, I don’t think we’ll see DFR on PC for quite a while. xD
Standalone however I think the Pico/Vive build is already OpenXR? Not entirely sure.
Variable rate shading I think they could do though? It was mentioned a looooong time ago. Developer Update - 2 September 2022