From my experience, the dealership will try to replace anything *but* the ECU, if they acknowledge the issue at all.
It's a bad combo: many people can't hear the sound (depending on how bad it is) + the ECU is rather expensive + Nissan doesn't have any official advisory about this + dealerships don't like to replace expensive parts just because of "some" noise.
In total, my car spent 3 weeks in the dealership so far and counting.
PS: Yes, the squeal is exactly the sound caps/transistors sometimes make. Audible spectrum FFT analysis shows one single freq @ ~9kHz. The noise starts/stops with engine on/off, simple as that. Sometimes the engine needs to get warm a bit before it starts (~10mins running). Idling/gunned not much difference.