1.07 billion colors are only possible with 10-bit color support: Apple doesn't support 10-bit color (yet) in their operating system(s) so far, and haven't made any comments suggesting that they plan to.
So, unfortunately, it would be a waste of one's money if they were to purchase a high-gamut display (like the Sharp 4K monitor that Apple currently offers with the Mac Pro) as the operating system will only render 8-bit color (16.7 million colors) on the display. It makes more sense for a Mac user to buy a cheaper monitor that supports 16.7 million colors, as those displays tend to be ⅓ of the price of those that support 1.07 billion colors.
As a professional who requires high-gamut color support, I found this pretty disappointing and sent Apple a plea to introduce this feature at https://www.apple.com/feedback/macosx.ht....
Note: Windows has supported 10-bit color since Windows 7... Come on Apple!