Here are a few notable changes that Ricci points out in his video. Firstly, there is now the ability to hide all the information that appears in the viewfinder or on the back of the LCD while shooting. This includes information like how many shots are left on the card, the exposure meter, remaining battery life, etc. This was a requested feature that came mostly from those shooting video with the Z 6 and Z 7, as some of the information would block the edges of the frame. The ability to toggle this view on and off is customizable to a button of your choice.
Thanks to the addition of another slot over the original Nikon Z 6 and Z 7, you now have the ability to adjust how those two card work. You get the standard overflow, backup, and RAW and JPEG options now.
There are additional autofocus options to manage the number of new ways that the camera can use its AF system, and the interval timer also sees some updated features that will appeal to timelapsers like automatically turning autofocus off during interval capture.
You can further customize the “i Menu” to give you quick access to a lot of options to customize the camera to your specific needs.
Here is a full video by Ricci Talks that goes in deep dive into the menu changes for the cameras.