While I respect the Linux on Mobile work, I believe that AOSP is a lot better, with a much better security model.

Remember that GrapheneOS is not Android: it's an AOSP-based OS.

You’re not wrong. The thing that bothers me is that AOSP is being developed behind close doors and controlled by a single company which wields way too much power and control over our daily lives, and which has a track record of abusing that power.