You can call any IG feature in C3 since the full sdk is included. You just need js, for the missing events.
You can not use any other ads than Meta in IG. I can though see IG added banners in some recent sdk update. So you should be able to call them with js. If you update sdk version in the export files
IG is also invite only now, so if you are not approved you cannot release any game at all anyway. So the plugin is not used so much any longer..