Arbitrary (user configurable) placement and spacing of buttons within toolbar

I searched for this feature, but all I saw were requests regarding the bookmarks bar. This has nothing to do with bookmarks. Also, just as an aside, users should be actively discouraged from posting lists of features they want to see in a single, ambiguously-titled post. Most egregious example: What it would take for me to use Brave as my default browser

Examples of where/how this feature is already implemented:

  1. Safari
  2. Firefox
  3. JetBrains IDEs
  4. MS Office
    … et cetera ad nauseam

Screenshots of some of those implementations:

Safari:

Firefox: