Thanks! I didn't use any screenshots as sources, because I a) wanted to scrape all possible options, b) want to make sure the default is really what you would get after a fresh install and c) was afraid that a screenshot might introduce some kind of color drift, compared to the original value the OS defines.

I mostly used things like the fantastic Virtual OS Museum (https://virtualosmuseum.org/), run-in-browser VMs like PCJs Machines (https://www.pcjs.org/blog/2015/09/21/) or real installations inside a VM. I tried to avoid using Color Pickers etc. and read the actual value from the OS somehow (e.g. copy the HEX value shown in the UI), but in some cases, I had to go with the macOS Digital Colour Meter (set to sRGB).