I'm not going to suggest third parties can't screw with a phone and make it effectively unusable, but why isn't emergency calling a separate code path in the dialler app and OS that just ignores everything that third parties have done? It should be impossible to change the behaviour of that small bit of the phone. Don't fire any OS level events, don't call any callbacks, ignore any registered intents.

This is on a Pixel. Google can have complete control of the OS and dialler if they want to. They should be able to effectively isolate this from the rest of the phone. Blaming third parties doesn't really explain it.