Interestingly I recently had a chance to experience a tech advantage over an older camera at my daughter's wedding. There was an official wedding photographer with two Z6 bodies. He was using Nikon 85mm 1.8 with an adaptor one one body and I took along my old D7100 with the exact same lens eg. Nikon 85 1.8.Technology will never trump vision & skill.
As the father of the bride I didn't have the opportunity to take as many shots as he did, however there was occasions where we took the same shot. I was interested to see his results which I was recently able to download. I can say with confidence that there is no noticeable between his shots and mine. Did he have an advantage?...........I'm really not sure......maybe he could obtain eye focus quicker than me. However all the shots I compared were stationary shots therefore not sure it you could say that he did.
I have have also watched several videos that state Nikon mirrorless bodies are lacking behind in the autofocus capabilities of both Sony and Canon. I have no idea if this is true or not.
So my point is that maybe the newer eye focus will result in more keepers for stationary subjects but will it work any better than say a D850 or D500 for moving subjects.
I assume the Z9 and Z8 may be better than the earlier mirrorless bodies but unless eye focus is a must for someone, I'm not sure technology in this price band would have that much of an advantage for weddings.