Note that there are no officially released specifications about the Z6 II and Z7 II. All that exist are rumor site posts and they are certainly not the same as "announced" features. It could be stuff that someone made up in their basement for all we know.
I think it's a reasonable guess that limited processing power has been the reason why the Z6/7 don't have as fast autofocus as some other cameras and also has limited the burst performance (ability to display EVF updates at higher fps rates, ability to clear the data in the buffer to card, ability to track moving subjects during a burst, etc.) so if Nikon indeed put in two processors, I would consider it by itself a major update.
The dual card slots and vertical grip with controls, if present, address the other criticized aspects of the original Z6 and Z7. So, basically, chances are that all the major limitations of the first-generation products are resolved in the II models. That would be pretty good, considering that they have to keep coming up with stuff to improve to continue selling cameras after the second-generation models. What else is there to do? The competition doesn't have lit buttons. There is only so much space in a tiny camera housing.