Don't sleep on JPEG XL. It's used under the hood within DNG files (at least, it's an option, Adobe DNG Converter can leverage it, including by the CLI), DxO PureRAW leverages it in the latest versions. Apple Photos can view them, and I think it's been the compression methodology used inside their ProRAW DNGs for a while (which probably by default makes it one of the worlds most popular image compressors for RAW files). I've had a lot of success using it for various things. Had some issues surrounding metadata but that may be user error on my part.
Those are good venues to sneak JPEG XL into the mainstream. It would be a pity if it became another JPEG 2000. On the other hand, JPEG 2000 was probably just too advanced and computationally complex to be widely adopted at the time. Sometimes I look back at it and, after all the extensions and revisions, it feels like it has everything—but it’s still a niche codec. A cautionary tale, and a pattern that tends to repeat itself with codecs...
On top of being much more complex to encode and decode, and being encumbered by patents, JPEG 2000 was only marginally better than JPEG in terms of quality vs. size. At the time it came out, it wasn't worth using; nowadays it's thoroughly outclassed by any newer image codec (JPEG XL, WebP, HEIC, etc).
DNG is more a container in which you can store lots of different think and not only RAW images.
For example PureRaw output Linear DNG that is not a RAW anymore. In the same way ProRaw is not a RAW image dispite it's name. But yes PureRaw and some ProRaw are compressed internally with jxl.
JXL is great on a variety of images with great PSNR across the board. Surprised it took browsers a good long time to ship it (removed and brought it back)
You can get way better perceptual compression at much much tinier sizes though. This is where a lot of user studies and research could play out.
If you've read that article out, you might want to take a look at alternative approaches to compressing images with similar principles.
https://github.com/guilt/MLL is a recent reimplementation of an old idea; If you quantize out the image blocks you could emit them in vector coordinates and have perceptually similar results at a fraction of the size with very decent signal preservation.
