@Carmelo_DrRaw @Elle I read through lots of PDFs today. I didn’t keep track of them but here is one that seems to address much of it: https://www.itu.int/dms_pub/itu-r/opb/rep/R-REP-BT.2390-1-2016-PDF-E.pdf, which I only skimmed just now, sorry. However, the obsessive reading spree was on my small-screened and half-touch-broken phone, while busy doing something else. 
I might have gotten things mixed up because of that and the fact that there is so much info out there, but here are some points that might be relevant. Again, I am speaking in non-technical possibly vague terms. My purpose in threads like these is to brainstorm and / or provide sanity to a very complex subject. I will leave the technical efforts and battles to the rest of you. 
1. There are two standard transfer functions called Perceptual Quantizer (PQ) and Hybrid Log-Gamma (HLG). Each has its strengths and weaknesses. Briefly, PQ is an absolute display-referred signal; HLG is a relative scene-referred signal. The former needs metadata and isn’t backwards compatible with SDR displays; the latter is. Depending on the rest of the specs, esp. for PQ, there is a preferable type of HDR display and surround. A common measure is the amount of nits.
Looking into this would probably answer @Carmelo_DrRaw’s question. Many documents show what happens on various displays and surrounds combinations. Pretty graphs and descriptions. Makes me want to root for one or the other as if it were a competition. 
(I am leaning toward HLG 
).
2. Next we have @Elle’s link and comments.
Stupid Github, now, won’t let me search from its front page without logging in. MS’s handiwork? 
These commits and their comments show how variable the standards could be. There were PDFs talking about the choices made by various entities, workflows and devices. The discussion varies depending on the perspectives of the document or slideshow publisher but you kind of get a gist of the common themes are among the infographs, tables and figures.
@Elle’s particular linked document HDR.pdf gives examples in the form of waveforms, which is very helpful from our perspective. Photographers tend to use the histogram (JPG); videographers use waveforms (and other scopes) to quickly gauge where the DR, among other things, is. As you look at the images, to me at least, it is easy to understand why “there is no agreed upon diffuse white point level”. It has to do with a lot of things, a few which I will briefly list in the next paragraph.
Just as we need to make decisions when we look at the camera’s histogram (generally generated by the preview JPG, not the raw!), the videographer has to look at the scopes to determine and decide on the DR and the distribution of tones, among other things. Choices need to be made (edit: and we need to consider leaving some data and perceptual headroom too). Hopefully consistent ones per batch or project. These decisions are based on a number of factors including personal experience and tastes; client and product expectations; workflow; and ultimate output and viewing conditions. There is a lot to be said about point #2 but I have to rest after a tough day!
and looking at my spreadsheet I already found a problem. But solving that problem won’t address whatever type of profile 
