(I dont bother with encrypted messenging apps. I prefer to assume that anything I do on my phone is doubleplus unprivate. If I want privacy, I head over to my computer.)
Competition is Qubes but that has usability issues and does not have good hardware security.
When I'm at home I don't wanna use a virtual keyboard on a 6.3" (or 7.9 unfolded). I just want to use my triple monitor PC setup with a real keyboard and a wealth of display space.
Mobile is cool for on the go but a productivity killer.
Google Pixels have no evidence of a hardware backdoor when a desktop is proven to be much less secure against remote and local exploitation.
It has been shown through leaks that Pixels running GrapheneOS are the most secure against Cellebrite in AFU. GrapheneOS was the first to implement a reboot timer feature which brings the device to BFU (much more secure) and then Android and iOS copied it (with longer, non-customizable duration).
You can inspect network traffic to see that GrapheneOS phones only connect to GrapheneOS-run services.
Here's a team member's thoughts: https://discuss.grapheneos.org/d/10150-not-your-average-why-...
I think it's entirely possible that a compromised Titan module (whether such code ships with the device or is updated at a later point) could leak keys via some covert method, and possibly transmit via the baseband or through some other application/method where the OS is not really aware of what's going on.