I went to carphone warehouse today.... unfortunately I spotted all of these issues... its really odd the screen is wildly inconsistent, dull, and overly warm... I'll say this though, I do believe Googles reasoning for sRGB... if you notice inside applications the blues are way more punchy( as opposed to in the home screen/OS general) - clearly this is where the app colour profile takes over.... the whole issue may be at least partly resolvable by software update.
Unfortunately, my decision has been made... performance is amazing but the screen is poor...and ultimately that renders the camera useless as the screen is effectively the viewfinder and the output. I really wanted to love it.
I wonder if you are making "a mountain out of a mole hill". I too have read about the graininess issue on LG OLED phone screens but wonder if the average user will ever notice unless they are really trained to look for this issue.
Why do I say this?
I have read a number of the reviews and comments. Boiling it down, it seems to me that the most obvious case where this issue is to be noticed is in a dark room with zero percent brightness, which occurs in the "night use" case. When there is a solid background you will see the grain if you look hard at it. If you are not in the night use case, the "grain" is much less noticeable.
In one review I read it said the photos of the "grain" are meant to be exaggerated comparisons rather than a realistic representation of what the screen looks like in the dark. So I ask myself, how useful is this in general for most users and how useful is this really in my use case. I do not intend to use the phone mainly in the night use case, in fact I use it in this case rarely. I do like to sleep at night and not view my phone with such a critical eye.
When I saw the screen up close the other day (during the day) I was very pleased with it. Each person will need to decide this issue themselves but for me the "grain" issue is a non-issue.