There are three RAW file formats for a Z 8:

But, as léonie, says, you're out of luck using any of them in Monterey. And I'm not holding my breath waiting for future support of High Efficiency compression.
I use High Efficiency*, which is not supported even in new OSs. But I don't expect the Photos app to be very useful for RAW files anyway. Photos doesn't seem to offer anything special for RAW files.
I have my Z 8 save jpgs on the SD card and NEF files on the CFexpress card, and I import the jpgs to Photos. I use those jpgs to curate my pictures, rejecting most of them. Many of the jpgs are lovely on their own, But for the ones that seem like they could benefit from RAW information I edit them with either Nikon's NX studio (free!) or Adobe's Lightroom classic (subscription--bah!) I get the best results I can for these selected images with these RAW editors, and I save a jpg that I can import to Photos. I sometimes find that I can further improve the image some with Photos' own editor.
I'm using an app called Raw Right Away to show NEF thumbnails and allow QuickLook on NEF files.
Here is a link to Adobe's Digital Negative (DNG) converter that makes a universally acceptable RAW picture file. This is the format that Lightroom uses when it creates a new (edited) RAW file, and Apple and Photos supports it. The converter is free:
https://helpx.adobe.com/camera-raw/using/adobe-dng-converter.html