Last time I mentioned this, someone replied there's already an Apple idea (or was it a patent) for this.
> "When a contact calls you and you're both using Phone by Google, their device sends a silent confirmation signal in real time to your device to verify the call is legitimate and truly coming from the contact's device," Google writes in a blog explaining the new feature. "Because this digital handshake uses end-to-end encrypted Rich Communication Services (RCS) technology, it is completely private."
On the outside they present that as a feature for your safety, but how common is really that someone can pretend to be one of your friends or family member and mid call you don't notice that it is not the case?
But in reality, the goal is to have users not using Android being discriminated with some checkmark or something like that. And try to push users to enable RCS that no one really wants.