It's already pluginized due to
In 4.0.0, remove the plugin from core and put it in cordova-plugins. Possibility of release as a core plugin, not sure.
This will include functionality to configure the callback function that is called, which is currently a global handleOpenURL function.
Remove/edit the note here as well: https://github.com/apache/cordova-ios/blob/b3c26fcd598da7c84f020f5a6b9309fe638cbb5d/guides/Cordova%20Custom%20URL%20Scheme%20Handling.md