A lot depends upon which F-mount Nikon lenses one has, as not all of them will continue to work in the same way on the new camera with the FTZ adapter; some will no longer be AF, for instance, and others won't work at all. Somewhere there is a compatibility list which describes which F-mount lenses function in which way with the FTZ adapter. For me that was a show-stopper, plus the relative paucity of native lenses, especially in the beginning.
As it happens, four lenses that I have happily using as native Sony FE-mount lenses (50mm macro, 90mm macro, 100-400mm, and 200-600mm) on my A7R IV are still not available as native Nikon Z lenses in their respective equivalent ranges. If back in November 2019 I had decided to stay with Nikon and go with the Z series I'd still be waiting for those lenses to eventually come down the pipeline....
As it happens, four lenses that I have happily using as native Sony FE-mount lenses (50mm macro, 90mm macro, 100-400mm, and 200-600mm) on my A7R IV are still not available as native Nikon Z lenses in their respective equivalent ranges. If back in November 2019 I had decided to stay with Nikon and go with the Z series I'd still be waiting for those lenses to eventually come down the pipeline....