I managed to get around ~7W idle on a 2024 dgpu/igpu laptop, with room to further optimize. From my limited casual checks (nowhere near proper benchmark), it's better than windows.

But yes it's an area that still requires tweaking, which is a cost I don't want to incur. Also just within this year I got a regression (later fixed) because of a bug in nvidia-open driver so it stopped going into low power state giving me a toaster on the go. These are still very obscure to root cause and fix.