Its actually really simple. Just do the math.
So forget TFs and all that to begin with, lets look at the raw numbers. Lets take a PS6 game for instance, this game is running natively at 1440p@60fps. PSSRx is taking that to 4K. So, ~40TF / 640GB/s / 26GB of RAM is getting you 1440p@60fps.
But now let's look at that raw pixel count, and compare 1440p to other lower internal resolutions.
1440p is;
- 7.1 x 540p
- 9 x 480p
- 16 x 360p
You see how that works? So technically, for the most part, on the GPU side of things, a "PS6 handheld" can be as much as 16x weaker than a PS6 to run the same game but at 360p and use PSSR to upscale that to 1080p. Cannis is probably around 6-8 times weaker when you factor in RAM capacity, bandwidth, CPU and GPU core count and clocks...etc. But thats fine, when you consider what internal rez cannis would be working with.