Open the Shortcuts app
Tap the plus icon
Tap Add Action
Search for and select Open App
Tap App and choose the app you want
Tap the share icon or the settings icon
Tap Add to Home Screen
Tap the app icon next to the name
Choose Take Photo, Choose Photo, or Choose File
Select the new icon image
Rename the shortcut if desired
Tap Add
Repeat for each app icon you want to change