I've been doing a lot of reading on this topic across the internet and have settled in on what I find to be excellent results for my 85" Sony X900H (which does not have HGIG settings). The PS5 HDR calibration on the set was done in a pitch black room:
Step 1: It's possible to adjust this so that the sun image will baaaaaaaaaarely show up. For this reason, it wouldn't make sense to go one notch more so that it is fully invisible because of how the PS5 seems to jump forward or backwards a lot of nits with each click. The goal is to maximize the ability of the HDTV, so getting the first setting as close to invisible as possible works well.
Step 2: Vincent's adjustments in the video are done on an HGIG capable set, and he said step two should be the same as the first step. That doesn't work for my non-HGIG X900H. As I click the the values enough, I have to choose between either a faint sun image that is very dim but clearly visible, or a fully invisible sun. From what I read on the 'net, I will benefit more by choosing the invisible option since it will allow the full capability of the HDTV to be used. Yes, there is some extra nit info that can't be used, but unlike if I had made the first setting fully invisible, the jump to the next click here isn't nearly as dramatic, so there won't be any significant issues.
Step 3: Vincent kinda mentions the type of HDTVs that should have this at zero, but I read a more expanded explanation. Putting it at zero applies to OLEDs as well as LEDs that have dimming zones (which the X900H does have). In both types of displays, full black is properly acknowledged with step 3 set at zero.
As I said, the image is absolutely gorgeous once I did it this way for my X900H.