Harshy. I apply the Duiker filmic equation uniformly to the three channels.
The input conditions deserve note. In my current workflow, tone curve is applied to the data in linear camera colorspace, with only black subtract, white balance, demosaic, and in this case highlight reconstruct to tame the blown sun.
Bit surreal but hey…
Edit…maybe a bit more toned down…
_DSF3698.RAF.xmp (17.1 KB)
Thank you very much for several rendering/editing suggestions. I found the result achieved by @spidermonkey very realistic. He/she uses the sigmoid module (?) of the latest DT release. On my PC I use DT 4.0.1. released via the website that does not include sigmoid. I will examine the settings - xmp file is provided, thank you for that - as soon as a new DT version with sigmoid is available at the DT website.
Motivated by some good results I tried to improve my image. Here is a second try:
In the “filmic rgb” module “white relative exposure” slider is in this case very sensitive to change highlights around the sun. I could achieve this result almost using this slider. I also added some noise to highlights and # of iterations (here 1) of high-quality reconstruction plays also an important role.
The corresponding new XMP file is included.
_DSF3698_01.RAF.xmp (23.2 KB)
I like your resulting image (the first one; Aurelien’s dtUCS), too. But, I am not familiar with that DT module shown at right. 
I think there is still the possibility to make the sun interesting. I tried to adjust the transition to leave it as intact as possible and with a small ring/flare around it as you might see sometime…otherwise as some have chosen to do you let it blow out or you blur it and color it and end up with a blob in the sky… I didn’t spend as much time on the overall color and tone so my edits could have been better I am sure but I think to me the sun looks better blown out or with some sort of bright center if it can be managed rather than a diffuse blob of color to hide the fact that it is blown out… It will be nice to see even more edits and see how people handle the sun… the HLR sliders in filmic do offer some options which is nice. I tried this image in ON1 photo and it really had no answer but to colorize the blow out with a luminosity mask…
I might go back and try the guided LHLR and see if as AP presented it can be used with filmic to restore a gradient in the highlights… Thanks for a great image… makes me want to be at the beach
I am happy that I shared this photo for DT editing. It is incredible what you can do nowadays using a RAW file. 10 years ago the camera would just blow up the sun and the surrounding sky. DT is very powerful to handle such difficult images. I am still a beginner regarding DT I feel.
This is how far I was able to go on DT 4.0.1
But I really like the edits of @spidermonkey and @7osema
Out of curiosity - I did put the file in Lightroom Classic. But this is without any modification - simply import and export. And the items of interest to me are the blown out sunshine and the mountain below it.
Looking at the results from @spidermonkey - sigmoid based I am very interested to see the final product when it is released.
On the left - the history shows that nothing is done to the image.
Slight sidetrack from the subject. Adobe developed interesting AI based masks in Lightroom (subject selection / face detection etc.). While I do appreciate the masks in DT - If somebody has the knowledge how to do that - it would be quite a benefit (if ever - I expect it maybe a huge undertaking).
As far as I know, both sigmoid and inpaint highlight reconstruction will be available in 4.2 release.
I ended up having to do very little to the image to make it look good, so credit should go to the developers.
I tried one of the weekly windows builds of 4.1 using a different config folder and it all behaved nicely (except for exporting this file - perhaps because it is fuji).
Just to clarify, I think @hanatos 's screen shot is showing the new application, vkdt, not darktable… but that is about the limit of my knowledge - except that it is fast 
Just for context and support of how good the FOSS stuff can be…
ON1
Default opening
Then enabling their hue based highlight recovery…
Here is pro neg…
Just for context …
I tried to recontruct the highlights to my taste, keeping the sun disc visible, plus a tighter crop.
DT 4.1
Fun to see such good results with the sigmoid module @spidermonkey !
And then the Lightroom and ON1 results to compare with
My observation and not from this is: how would I do a edit with a visible sun disc with the sigmoid module as my display transform? That will require some dynamic range editing to bring the neighborhood around the sun down in exposure while not making the foreground black. Is this possible with the tone equalizer currently?
For example with “rgb levels”
Sigmoid ON and rgb levels: OFF:
Rgb levels won’t work here, especially in from of sigmoid as that module expects bounded display referred data. We need to work with methods that change the exposure locally. Tone equalizer, masked exposure, graduated filter, contrast in color balance rgb, etc.
@jandren I have had a go at making the sun disc more visible using tone equaliser here:
I reduced the edges refinement to very low to avoid banding
and adjusted the smoothing diameter to get a balance between ugly banding or the sun disc being smoothed too much.
Adjust highlights_01.RAF.xmp (12.8 KB)
I think darktable uses the wrong raw white level for this file:
A tiny reduction changes clipping detection considerably:
Two silhouette approaches, one with filmic, one with sigmoid. For both, I found the reds overwhelming, and pushed them back using the simple channel mixer preset of color calibration. I used a separate instance because I found it gave nicer colours; if memory serves me well, and I understood correctly, on the primary (chromatic adaptation) instance, the R, G and B channels are not really R, G and B (see Color calibration - colorfulness - #17 by anon41087856).
