@Loki, thank you very much for your great post (as quite needed response)!
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Nice, yet now that we know (very important post #84 related) that R9 is at around 0%, replacement of current COBs would be mandatory (those are of standardized size anyway) for the next devices (yes, please, as rather no investment than buying poor product, if and when making some photos related) even before any workaround in sight to be taken.
It’s not that uncommon. Flash can serve as an additional, not primary, source of light. I don’t know if anyone uses this technique with phones though. I normally don’t use flash in my favorite kind of photography, so I wouldn’t know.
EDIT: meaning that there are advantages to flash matching the temperature of common light sources.
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I can see it useful for making shadows less obvious, but I am not sure if 2 COBs on a phone can make much difference outdoors. If it would be helpful, it would have to be indoor lighting that uses 5000K, which might be common in retail, but not in households. I am sure that there are a few situations where it can be helpful. I would guess that you would need a more powerful flash. At that point, most people are not using their phone camera. But I could see a market for a USB flash to use with a smartphone for times where you do not want to carry a dedicated camera around, but a compact, limited-use purpose-built flash would fit.
These were taken with just the torch light with the new white balance preset from the merge request above:
That was the birch model. Because most of Purism’s stuff is black (which is why I included the green and blue circuit boards), and black does not test white balance that well, I also took this picture:
I used the auto setting for most parameters. I probably could have dialed in a few things better. For the book, the colors are, for the most part, naturally that dull. You can see examples on the Internet to compare.
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This reminds me - our photos are skewed towards warmer colors because our color calibration matrix is done really badly (by none other but myself).
Does anyone of you folks maybe have access to a color calibration chart and could take a photo of it (with a L5 of course) illuminated by a D65 source? 
(there are other reasons too, like using XYZ scaling instead of something like Bradford for chromatic adaptation, but first things first)
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I can ask the colleague who works in the lighting lab.
But I haven’t seen them use a light source yet, so far they have always measured the color space and brightness of LEDs when I was there.
(and my phone must work properly again at the moment I have a problem with battery and charge).
I took some calibration photos but didn’t get around to successfully creating a matrix yet.
I can create a matrix, I just need a well-exposed and in-focus photo that’s illuminated by measurable D65.
Best I can offer is semi-controlled cloudless summer sunlight.
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I try to get something there, the colleague did not know if they have the source, but he asks.
Thanks! One tip - when taking the picture, make it so the tester is in the middle of the photo and takes only around 50% of the area (this way we don’t get color distortion from lens shading affecting the fields on the tester)
bad news guys, we don’t have a calibrated light source in the light lab. Sorry I would have liked to support.
No worries. There’s a calibrated source I have access to (just don’t know when), and now that I’ve been reminded, I’ll put some effort into this again to close the topic.
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FYI, as related (aldghough somewhat irrelevant here) to the NVSW219CT R9050 (where 50 relates to the R9 value), as built-into the NITECORE MT06MD flashlight:
Putting SmartArray L6 LED-Module 4W (12V) 6500K LED CRI=80 with 6NF2W757DR near Librem 5 main camera should be easily made. Yet I’d need to buy one + get ColorChecker and I do not mind to do this simple setup purchase (if necessary). @dos, just let me know what you think about such setup (would be useful for my needs anyway, and if recommended from your side, I’ll go ahead with this here related purchase).
EDIT: Using Fenix E01 V2.0 flashlight with the Cree XP-G2 S3 LED might be another simple approach for taking pictures, with Librem 5 camera, under D65.
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You probably know more than I do 
All I know about photography is what I learned when implementing color balance stuff in the camera app - and I already managed to forget a big chunk of it 
If you think that this is an adequate D65 source for taking a calibration photo and you don’t mind such purchase, then go for it!
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My initial point was that with manufacturing tolerances and variances together with the many environmental factors/parameters affecting performance, the measurable real world characteristics/metrics are most likely to be significantly different from anything provided by the manufacturer and that the manufacturer would never commit to guaranteeing exact numbers.
To determine whether or not a particular source is suitable to be used as a CIE D65 reference, you should look at the SSI (Spectral Similarity Index) value when comparing against CIE D65 SPD.
In the case of critical calibration, I am not aware of any solid state/LED sources that I would consider to have an SPD curve similar enough to that of CIE D65.
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Have been testing auto exposure/gain and autofocus. First two work great, auto white balance does not work since it is unstable going back and forth without converging somewhere. Also my images are saved in .tiff instead of .jpg using dcraw which is a little odd.
In order to have it perfect do you agree with getting LinearZ 280-26-D65 LED Module? Is it rated at 653?