While the support itself doesn’t necessarily mean OS-level toggle like the Steam Deck has right (which I believe is still at FSR 1), it still could be a nice touch for the titles that choose to implement FSR 4.
Maybe the community adds the OS-level support unofficially, somewhat similarly to Lossless Scaling right now (although perhaps for free). This is just my uneducated guesswork, please see this comment for proper expectations:
I am not saying you’re wrong, I’m trying to understand what you posted. But I see what you mean now. I was under the impression the training data was specifically for the specific upscaler so FSR4 would need at least FSR2 supported natively.
Oh, no no, I did not say or imply that. I was concerned about FSR 1 and the difference to the other upscalers. And the difference between the second new mode of FSR 4 that is not available on any other. So even if you have DLSS or FSR 3, you can only use the Temporal variant of FSR 4, not its ML-based variant (if I understand it correctly). At least that is what I said, so its probably true (self irony).