How to add spacing to list or enum without affecting linespacing?

As I said, it felt, and it mostly is a duplicate of How to control spacing between an outer enum and inner bullet list, so I just yonked How to control spacing between an outer enum and inner bullet list - #3 by Andrew and adapted it. It was too much, but then I reduced it to 0, and it looked correct, so I rolled with it. I’m definitely not sure how the logic works with this one, but the rest of the solution does make sense for the most part.