Linux phones are way less secure than Android phones. There already exist phone os like grapheneos or lineageos or calyxos that degoogle. Linux desktop and phone don't sandbox apps so if you install one malicious app it has access to all files on the phone your camera and so on. Even if you use flatpak the flatpak sandbox is weaker(easier to break out of) and the app dev of the flatpak app decide what permission it should have unlike on android where the user does so with major permissions like camera.