I did not try to imply that WhatsApp is secure or trustworthy. They will, of course, use as much data as they can. But that’s something out of control of the mobile phone. And if they wouldn’t pre-install WhatsApp, users will download it ASAP.

And suddenly all investors will spend billions to promote this tech.

One has nothing to do with the other. A properly configured Android is not going to leak any information to its apps. The problem comes with the customized Android a phone maker uses, where they do everything to gather data (or let others gather data if they pay for it).

So while the app itself is anything but privacy friendly, the phone is. So is GrapheneOS with WhatsApp.