I made a demo app with both in it except the icon. For the icon I filled the background with a red color in p3 color space that exactly matches the sRGB color [r:1,g:0,b:0]. On top of that I drew a star using the display p3 version of the color [1,0,0]. If the icon is displayed correctly in p3 color space you can see the red star because it looks brighter than the background. However, if the icon gets converted to sRGB you do not see the Star anymore because foreground and background look alike