Unofficial documentation for the iCloud Apple device image URL format

gistfile1.txt

https://statici.icloud.com/fmipmobile/deviceImages-9.0/iPhone/iPhone9,4-2-3-0/online-infobox__3x.png
                                                   A   B      C         D E F G

A: deviceImages version seems to determine the format of the image specifier (C, D, E, F)
B: device marketing name
C: device model identifier
D: front color (DeviceColor)
E: back color (DeviceEnclosureColor) (missing on very old devices)
F: color (device cover/backing/housing)?? (missing on older devices)
G: image variant
   online-sourcelist.png
   online-sourcelist__2x.png
   online-sourcelist__3x.png
   online-infobox.png
   online-infobox__2x.png
   online-infobox__3x.png
   
Examples:

Black iPhone 4S
https://statici.icloud.com/fmipmobile/deviceImages-9.0/iPhone/iPhone4,1-black/online-infobox__3x.png

Silver iPhone SE
https://statici.icloud.com/fmipmobile/deviceImages-9.0/iPhone/iPhone8,4-c8caca-dcdede/online-infobox__3x.png

White iPhone X
https://statici.icloud.com/fmipmobile/deviceImages-9.0/iPhone/iPhone10,6-1-2-0/online-infobox__3x.png

Black iPhone 8 Plus
https://statici.icloud.com/fmipmobile/deviceImages-9.0/iPhone/iPhone10,2-1-1-0/online-infobox__3x.png

Gold iPhone 8 Plus
https://statici.icloud.com/fmipmobile/deviceImages-9.0/iPhone/iPhone10,2-2-3-0/online-infobox__3x.png

Black HomePod
https://statici.icloud.com/fmipmobile/deviceImages-9.0/HomePod/AudioAccessory1,1-1-1-0/online-sourcelist__3x.png

White HomePod
https://statici.icloud.com/fmipmobile/deviceImages-9.0/HomePod/AudioAccessory1,1-2-2-0/online-sourcelist__3x.png

Gold iPad Air 2
https://statici.icloud.com/fmipmobile/deviceImages-9.0/iPad/iPad5,3-e1e4e3-e1ccb5/online-infobox__3x.png