I can totally follow you here.
Mirrorless auto focus is a very complicated matter, and not as "simple" as the auto focus on a traditional dslr, where Nikon led the pack I believe with the D5 and D500.
Still, I see a shortcoming in your assesment regarding Sony stacked sensor auto focus (A1) versus Nikon stacked sensor auto focus (Z8 and Z9) and that has all to do with the lenses you have tried.
-they lack the f2.8 and f4 brigh5 apertures that your Sony high end lenses have.
I see a noticeable difference between auto focus performance wide open at f4 (very fast and very accurate) and closed down to f6.3 when using the Sony 600GM. Often for that reason, I use it wide open even if light allows for stopping down.
-the lenses that you have tried have substantially inferior focus motors compared to the Sony GM lenses, which feature very fast, twin linear motors.
The Nikon lenses have single stepper motors, that are not nearly as fast to begin with.
So this comparison may not be totally fair to Nikon.
For that, you would have to try the Z400TC or Z600TC, with the same large, bright apertures and top end, fast focus motors that the Sony GM lenses have.