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:
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.