Nikon Z9 Compressed Raw Support in Apple Photos

No one outside of Apple knows what plans they have to support the other raw forms from this camera - or indeed, any camera. Apple don't announce these things in advance. Based on their behaviour it's not really a priority for them, so I would not expect them to add this. They don't don't support multiple raw formats for other cameras.

If storage is an issue you can run an Photos Library from an external drive formatted Mac OS Extended (Journaled) or apfs with no difficulty.

What gets sent to On1 is a tiff, that's what comes back and that's why you can see it subsequently.

I would wonder why, if you have On1, you're using Photos at all. On1 is a far more powerful application for the task and its raw support is independent of the OS.

It just seemed to me to be the kind of obvious technology Apple would leverage.

If they had any interest in Photography they might. While I'm pretty sure they have interest in people taking snaps with their phones and using the Cloud service to share them across their Apple devices, I'm not sure they have any interest beyond that.

That's a top-of-the-range camera you have, and frankly, Apple make Photos for folks shooting with iPhones and iPads to share easily. Just because Photos will decode the lossless raws doesn’t mean Apple have any interest in anything else the z9 does. They offer the bare minimum. They expect folks with expensive cameras to use 3rd party apps. They won't say that, of course, but actions (or in this case inactions) speak loudest.

I wouldn't regard Luminar as a serious app, but I do know that On1 and Lightroom (both versions) offer good sharing options, though you may need to read the help in either case. As a direct competitor to Photos, the Cloud version of Lightroom is well worth checking out, as is a nice clever app like Mylio.

I say this as, frankly, I do not honestly believe anything will change with Apple's support for your camera in Photos.

What hate? It's being realistic. Photos is very good at what it does, and what it does is very much aimed at supporting Apple's efforts to sell devices and services. It's the same with all the Apple consumer apps. They're limited by design - think of Pages: perfectly fine if you want to do a flyer or newsletter, or simple letter. Want to do more? Then you'll have a much better experience with apps like InDesign or Word. That way Apple can have something for the home user that still leaves room for 3rd party developers. Similarly with Photos. It does what it does, and does it at the right price point for what it does. But there is still room for 3rd party specialist developers aimed at the Pro / serious hobbyist shooter. So, you have Adobe, CaptureOne, On1, DxO at the top end of the market, Mylio somewhere in the middle, and at the less demanding end: Photos and perhaps the Google service, also free. That's how you have a healthy ecosystem around the Mac.