Nikon today released a beta of its webcam software for Mac. The Windows version (also a beta) was released a month ago. Be sure to read Notes section in the the System Requirements.
Added November 4: The software was updated to
version 1.0 today.
Supported cameras: Z7II, Z7, Z6II, Z6, Z5, Z50, D6, D5, D850, D810, D780, D750, D500, D7500, D7200, D5600, D5500, D5300 and D3500.