I haven't seen any noticeable difference between the D500 and Z6 FW 3.11. And you can't really get much more f/8.0 AF points and definitely no f/11 AF points with a DSLR, mirrorless AF points get significantly more light hitting them than a DSLR that has to split the light between the viewfinder and AF. I certainly didn't feel like I was missing shots with the Z6 last time I was out.
Should say though, I use the Z6 like I use the D500 with single point and group. Don't have animal eye AF yet, and hope the Z9 brings that along to the same magic level as Canon. If they don't, well I get a better single point and group.