Nikon D850

If you already have Mojave installed, you can convince yourself, that the Nikon D850 is supported by checking it in the -menu. Hold down the options key ⌥ while clicking the , then open the System Information. The installed RAW support is listed in the Software section of the System Information:

Yes, the Nikon D850 is on the list of supported cameras for Mojave: Digital camera RAW formats supported by iOS 12 and macOS Mojave - Apple Support