(Also, macOS won't display them in HDR, but will display EXR files in HDR. Some trivia for you.)
Do you consider the heic files from an iPhone hdr files rather than sdr, even though the extra brightness channel is stored as a separate channel rather than extending the range of rgb values?
linear DNG?
-> it's not compressed
"Lossless and lossy compression (optional): DNG support optional lossless and (since version 1.4) also lossy compression.[36] The lossy compression losses are practically imperceptible in real world images"
-> I don't think eg gaming content pipelines
Why is this a goalpost even??? In what context? Photogrammetry? DNG works just fine.... Or the actual engine itself? found one in 30 seconds of searching: https://github.com/EQMG/Acid
-> macOS won't display them in HDR
Well, that seems like a macOS problem
This is ridiculous at this point.
What I think they mean is that the iPhone camera app is the only one that takes an HDR photo of a scene a produces and HDR output image[0] that can be easily shared and viewed IN HDR on multiple devices.
I don't think that EXR is a particularly portable format (do phones even support viewing them in their native photo viewer/manager?) nor one with small file sizes.
The DNGs from Capture One or Lightroom have similar issues, they at least can be viewed on phones, but they do not show up as HDR images.
Other applications, e.g. Hugin, will produce and SDR image. It's based on an HDR image so it captures a wider dynamic range, but it does it through tone mapping back into a SDR image, rather than actually saving and showing the full dynamic range of the HDR image.
[0] I am not convinced that what the iPhone does with their heic images is really HDR, in the sense that the colors still seem to be stored in an SDR range.
But either way that’s changing the goal posts. Here is a consumer software doing what that iPhone does.
If that’s not to your liking, there is other software which produces 32bit float tiff images, those will support an even higher dynamic without the pain of EXR.