Nature Photographer?

I've been considering transitioning into more nature and wildlife photography and simultaneously updating my camera equipment. I decided to try out a Nikon Z6 Mark II along with an 180-600mm lens to see how it compares to my usual Sony setup, which was my first experience with mirrorless cameras. I must admit, I'm really enjoying the Nikon setup. Although my Sony gear is 7 years old, the Z6 Mark II is very user-friendly, and I'm familiar with most of the menu setup from my experience with Nikon DSLRs. Now that it seems I'm making the switch, the question is whether to go for the Z8 or Z9. here some sample pics