I don't think you understand.

If you spoof your resolution and window size to the degree that it's undetectable you effectively have to render it in that resolution.

Guess how websites make it so that they work on any resolution? They use relative units and whatnot that make it work that way, and all that is detectable one way or another. So you'd have to spoof it all in order to resist fingerprinting - and that is either going to break the rendering, or it's going to effectively render that website at that resolution, making it a bad experience for regular users either way.

I do wish this was an option for more "normal" browsers, and that they resisted fingerprinting better in some other ways, but you have to make serious compromises to make it work fully.