Today Nikon released the Mac version of their Webcam Utility beta version 0.9.0 that lets you use a Nikon camera as a webcam when connected to a computer via USB (the Windows version was already announced in August).
List of supported cameras:
- Nikon Z7
- Nikon Z6
- Nikon Z5
- Nikon Z50
- Nikon D6
- Nikon D850
- Nikon D780
- Nikon D500
- Nikon D7500
- Nikon D6500
For more information check this dedicated Nikon USA website.
Note: this is a beta release, operation has been tested with supported cameras but is not guaranteed.