I RMA’d 3 of the same monitor until I got a pair that had only 1 single dead pixel. It still bugs me, but it’s on my secondary screen and I can live with it. I did not do the same for my 70" TV, there were a few dead pixels and they’re not noticeable from the couch. I did consider it though.
I would personally send it back. You paid $500+ for it, you’re entitled to a non-defective product. If the second one has dead pixels, I’d probably send it back, but would be less inclined to so do on #3+ depending on where the pixel is.
If it’s a stuck pixel, you might be able to fix it with an online tool like this.
The Steam Deck and dock do not support CEC, as far as I’m aware.
There are however HDMI switches that can recognize when an input is powered on, so you could get the same result (with a slight delay) with a switch.