Saving space is well and good but for icons it’s secondary to how clear and usable the images themselves are.
Saving space is well and good but for icons it’s secondary to how clear and usable the images themselves are.
https://www.pushing-pixels.org/2011/11/04/about-those-vector...
I think Android’s (https://m2.material.io/design/iconography/product-icons.html...), Apple’s (https://developer.apple.com/design/human-interface-guideline...), and Microsoft’s (https://learn.microsoft.com/en-us/windows/apps/design/style/...) are more detailed than that.
(And yes, that’s comparing to the work of huge companies, but I don’t think that matters for deciding whether to call this ‘extensive’)
I also do not rule out that the tech choices they made (partly) drove the guidelines. It doesn’t make sense to proscribe things the OS cannot display.
Typically how they look is up to the designer, they can decide how many small details they want to put in to make the icon look better at a larger scale. Haiku seems to have gone with a kind 3d clipart style that isn't highly detailed.