I can confirm a couple of things. I have d850, and working off my XQD card where my fine jpeg + RAW L appear, when my card reader w/card attached to USB on my iMac. The jpeg and raw appear in Finder , under Untitled Device, which when opened reveal the two photo files. However, if I attach the USB cable from Camera to USB plugin in my Mac, nothing shows in my finder ie looks like , as you say, the Cameras, in the System Prefs have not yet picked up on recognizing the camera. Now, not sure, if it is this particular camera it is not picking up, or the new type of card it is not recognizing. Haven't tried this yet, with photos going to an SD card only.
Now, if I go to Photos app on iMac, under Devices, Untitled also shows up , so Photos is recognizing the camera/card there, however, the ONLY the Jpeg shows up (which I can import , with the big J label on it.). The RAW , Lformat is not showing up also, so doesn't appear so as I could import both. Only the jpeg shows up.
For now, looks like if I want photos to pickup RAW from my card, I will have to hook up to finder by seeing my photo files on Untitled, and then physically drag RAW to my Photos app, or third party app.
Hopefully I have shed some light what I am experiencing. Will keep following this post, and hopefully hear some cheers somewhere down the road on support for the 850
