Unity as a library iOS pass parameter on startup

Is it possible to pass parameters directly on startup?

We are currently using:
(void)runEmbeddedWithArgc:(int)argc argv:(char*[ ])argv appLaunchOpts:(NSDictionary*)appLaunchOpts;
However I couldn’t find any documentation for what those parameters are used. Can I read those in Unity?
I’ve tried with System.Environment.CommandLine but it seems empty.

Another way would be to use:
(void)sendMessageToGOWithName:(const char*)goName functionName:(const char*)name message:(const char*)msg;
But when can this be called? Immediatly after runEmbeddedWithArgc?
My guess would be that the scene hasn’t loaded yet. So we need to wait for that.

Can confirm sendMessageToGOWithName does work immediatly after runEmbeddedWithArgc