I bought a Z50II for my wife Gunver just before Christmas, there was at good offer with an extra battery and memory card.
It has now been used for a while for different things.
I took it out for at spin with the 100-400Z.
I donit not own a D500 anymore, but the experience was not very far from what I remember the the D500 did for BIF, with me at the controls, I an not a master in BIF, but do try at my local lake.
Now Thom Hogan has written his review of the Z50II, and I do agree apron. 90% with him. He is more nitpicking, but do like the camera.