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:
You can already use FSR4 on Steam Deck btw, no need to wait if you want to try it out!
https://steamdeckhq.com/news/we-can-now-use-fsr-4-on-the-steam-deck-for-better-visuals-with-a-power-tradeoff/
I already use it in combination with an portable monitor, scaling the output to 1080p - that’s my balcony setup ;-)
It’s possible this official release will have increased performance/quality, but even now it’s often better than the alternatives, on balance.
That’s what I hope for.
Below is my experience with FSR on Steam Deck LCD.
Most games that support FSR 3 already look good enough to me without the upscaling, more so in the non-demanding singleplayer setting where I might need it the most.
FSR 2 is just a smearfest at the level that provides any meaningful performance or battery life increase.
I often find myself going for FSR 1, either in-game or through SteamOS “Sharpen” scaling filter, which gives me a better quality image for what feels like identical performance and battery life to FSR 2.
Proton-CachyOS also can upgrade FSR3 games to FSR4 on RX 6000 and 7000 series of GPUs, and it works outside of the Steam Deck platform.
Optiscaler (with Windows games) also works if you need further tweaks or run into compatibility issues with the Proton level support.
That’s partially true, unfortunately some games do not work with the FSR4 upgrade via OptiScaler, and on top of that there’s a plausible risk of getting banned in games with anticheat