8k 60 All I is the bar. At $7000 to pay for the Sony sensor inside as usual they had to tame the high end video resolution. And of course it won't have 8k 60 but a limited 8k 30. Coming to the dance a year later doesn't get any kudos for innovation. Any competent engineer can copy and improve. The Sony A1 is the camera released with EVF blackouts for 4 months. We'll see what problems the Nikon comes with.
The Nikon Z9 has a 45MP stacked sensor, the A1 has a 50MP stacked sensor. It is not confirmed who is manufacturing the sensor yet and it could be Sony (Sony's camera devision are also a customer of the sensor division and Sony is likely a customer of Nikon for lithography equipment), Tower, or even fricken Canon. Not fabricating every component does not make it any less of a Nikon. They'll be non-Canon tech in the R3 and R5 too and that doesn't make them less Canon.