In addition to being a science teacher, I'm an assessment designer. When designing assessments for NGSS alignment we unpack the PEs. In short we look at what it would take for a student to meet the PE: what ideas do they need to understand, what vocab may come up, what proficiency would look like, and how the 3-dimensions play into the PE. Essentialy, almost everything you just stated!
A big help for this is using the evidence statements included with the standards. For example, if you visit the NGSS site and look at any standard, you'll see the evidence statement on the right side of the page: https://www.nextgenscience.org/pe/ms-ps1-1-matter-and-its-interactions. When you click on this, it will take you to a detailed break down of the standard and what is needed for a student to demonstrate they meet the PE.
However, it goes beyond this. There is also unpacking each of the dimensions of the standard. For this we need to think about what we need from the SEPs, DCIs, and CCCs. The appendices include this breakdown and progression. For example, here is the appendix for the SEP progression. This shows what I would need to focus on, or continue developing, for the students to meet the included SEP for a PE.
I agree that it is different than unpacking other standards. But, this process gives us a better insight into what it takes for a student to meet the PE. It's a lot! But I find it to be a very helpful process in narrowing the scope of a unit. You can always go beyond this, but the unpacking shows the minimum needed for students to demonstrate proficiency in the PE.
PS: Should also note that I'm not stating that all we're doing is teaching toward the PE. I know you're not saying that either. But some people get really fired up about it.