With respect, I think you're overthinking this susanstone2022, as Dolby has very clear in explaining everything about DV, through extensive documentation, how-to videos, manuals, and partner software like DaVinci Resolve also includes a deep manual explaining what all the trim adjustments do and how they should be understood and expected to be interpreted (there's a reason the Dolby DoVi license is so damn expensive, there's no hidden secrets or conspiracy here). Furthermore, you can clearly test all this, as RESET_9999 has done over many many hundreds of hours at this point, along with others like quietvoid who did all the incredible work reverse engineering Dolby Vision in the first place. How else would we even be able to know about the difference between all the players, LLDV vs TV-LED, and how it "should" look vs. when it's not if there was no understanding of the way DV works and is processed.
There is also the 4K Spears & Munsil disc available for further calibration and testing of TV-Led vs Player-Led by the likes of RESET, Vincent from HDTVTest and others in the industry. To put it most simply, just remember that Dolby Vision requires a special SDK/engine to be used and not unlike audio being able to "pass-through" to an AVR, the metadata for Dolby Vision also can "pass-through" and that's essentially what TV-Led is describing. It's technically possible some lower-end TV would not even properly license or play DV metadata but that's why folks like RESET test on multiple displays and Dolby obviously has a relationship with the likes of Sony and LG to ensure their top-end models properly implement Dolby Vision in TV-Led mode, at least with their own Blu-ray players and possibly major streaming apps.
Hopefully that makes sense, there are times to be skeptical, but this is not really one of them, as RESET, quietvoid (and Vince from HDTVTest etc.) don't work for Dolby and have put all of the labour and research required to understand and test Dolby Vision as objectively as possible, so you don't have to.
