Absolutism isn't helpful IMHO, there is no true security in this world only degrees of trust and risk. You can always go one step further in securing a product but the first step still matters.
I think there's real value in companies implementing e2e (and it's hard! it's super hard politically to get this done when the business sees little value for the effort and I know this because I've successfully fought to get e2e into a product).
The reality from my point of view is that it takes idealists inside to convince a commercial entity to lock themselves out of value (commercial surveillance) they could capture. I find a company's stance on e2e to be a valuable signal.
What you want belongs as an operating system or app distribution mechanism concern. A third party OS extension might make sense. Even that's a bit fraught if there is any kind of dynamic code execution (aka code that appears at runtime, say, a web view).
https://faq.whatsapp.com/en/general/26000050
Something is being watched. I imagine they are hashing images and comparing them to a database.
Thank you.
Except that there is no way to prove this. There is no way to prove that it isn't also sending a copy from the client back to the server. Whatsapp could deploy individualized specific clients to target users, perhaps at the behest of governments. The only full answer is totally open-source software with users able to cryptographically verify that they are downloading and running the same software as everyone else.