Color me skeptical. You seem 1000% convinced that the Nikon sensor is some sort of incredible game changer. But, I'm not seeing a lot of specifics about what you think it does, nor are you citing reviewers who have tried it who share your unbridled enthusiasm. (I'm sure many will talk up the camera, as they do with every other camera, because that's how they attract eyeballs to their videos and sponsors to their sites.)
As I said before, the Z8 sounds like a nice camera (I wonder if Nikon regrets picking a name that has become associated with the worlds worst terrorist regime) but the over-the-top claims about how it changes everything sounds like hyperbole to me.
Maybe it's because I've seen generation after generation of cameras that were supposed to change everything, that didn't. Maybe because I've bought into the hype in the past and even tried to convince myself it was real. Maybe because I've seen slow, steady improvements that are worthwhile, but few true "game changers." Maybe because I use both an R3 and an R5 and I've never once felt like the sensor was the critical difference between the two. Yes, the R3 is a great camera and I love it for sports shooting, but I honestly didn't notice all that much difference from the 1DxIII (other than the size, weight and convenience of having a single RF mount system.)
I'm not knocking the camera. But, you would have to do a lot more to convince me it is the game changer you claim it to be. Instead I think most people will look at it and see a Nikon R5.
It doesn't change the game in terms of new features, everything it can do has been done by the Z9. It changes the game because it does it in a price segment that was prohibitive before. It does things no camera in it price range can do. That is... by definition game changing. Some will argue Olympus started this, but Nikon is going to cement it.
However, if you don't need those features, you will not feel the same. If a fast sensor isn't apart of your photography it shouldn't mean anything to you and that is fine. For some people the Z6 and Z7 were perfect cameras. Different stroke for different folks.
Just understand, fast sensors enable the makers to engineer less tradeoffs. Rolling shutter is the biggest benefit. Take a shot of a swinging golf club with an R5/R6/R6 II/R7 etc.. and you will see what I'm talking about. Sure, you can shoot it with the mechanical shutter, but now you lose the higher speeds and quiet shutter release options. Or take a shot of a bird that's flying by, in the high speed mode you will be distorting your photo turning straight lines in to diagonals or you be stuck in mechanical shutter with its limitations. Even the R5 and R6 II will still distort regardless if it isn't "that bad". Take a shot of a bird taking off and look at the wing tips, if you are using e-shutter there will be an odd banding. No fix for this issue without using a fast stacked sensor or mechanical shutter. You ever take a photo of a still object only to find as you flip through the photos the still subjects is warping? That's not an issue for a stacked sensor. Also, non-stacked sensors don't easily sync with flashes in e-shutter, honestly not sure if its even possible. The R3's 180 FPS and the Z9's 120 FPS modes are only available because of their ability to move data off the sensor at high speeds. Another example of the benefits of stacked sensors are the higher DR and bit depth in high speed modes.
I can go on and on, but the simple matter is, if you have to choose from a camera with a fast sensor or without, I'd prefer the fast sensor. Being only $100 MSRP more expensive is significant because its been long thought that a stacked sensor cost a manufacturer significantly more (my guess has been approximately $500 more) to put it in a camera. Speaking plainly, this is a big deal because I see this starting a shift in moving to stacked sensors in the pro-sumer market. That's likely to define what manufacturers do next. Even more surprising, I'm not sure what this means for the top end of the market, because its hard to make a $6,500 camera that barely matches a $4,000 one.