I'm a recent (1yr anniversary) Nikon convert, from Canon. When I sold all me Canon gear, I had full intentions of getting a D500, D850, TC's, all the standard lenses (including a 600F4). When I went to gather my new gear, my buddy at the camera store slid the 1st Z7 that had come to north TX in front of me and suggested I try it rather than the D850. At the time, nobody knew much about them and when I asked about focus modes, acquisition, & lock he assured me that it was "at least as good as the D850".
Having already purchased a D500 & 200-500 (& ordered a 500PF) for my wife, I knew what I wanted with regard to focus characteristics. Her D500 was better than the 1Dx Mk II, 5DIV, & 7DII I had just sold.
When I got the Z7 home & began to play with it, I was immediately underwhelmed by the exact things I had asked about - Focus Acquisition, Lock, & Retention. I played with it for a couple days & decided it was not going to work for me, as wildlife photography (particularly birding) is what I do most. Luckily for me, they swapped the Z7 for a D850 - no questions asked.
As time passed & the Z6 came out, I paid close attention to what folks were doing with it and the results they were getting. One of my shooting buddies is a lifetime Nikon Pro & he's been doing some neat video work with the Z6 so I figured I'd give it a go. I actually like the Z6 a lot. It's a truly different shooting style & strategy, but it's quite capable.
It'll be a long time before I'd consider not having either the D500 or 850 along, but I've been taking the Z6 out most of the time with a different FL than the DSLR so it's been a bit of a phased approach.
Again, congrats on your Z6!
PhilM