The much maligned “Trusted Computing” idea requires that the party you are supposed to trust deserves to be trusted, and Google is DEFINITELY NOT worthy of being trusted, this is a naked power grab to destroy the open web for Google’s ad profits no matter the consequences, this would put heavy surveillance in Google’s hands, this would eliminate ad-blocking, this would break any and all accessibility features, this would obliterate any competing platform, this is very much opposed to what the web is.
On Modern Macs, the process is somewhat convoluted, but you are able to boot into a custom compiled boot loader / operating system while secure boot is enabled. It just needs a few minor hoops to sign the boot loader - steps that would be difficult to social engineer around but perfectly reasonable to do them intentionally if installing an alternate operating system is your thing.
iPhone is, of course, a different story. Hopefully that changes some day. The CPU and boot process is the same as a Mac, so there’s no reason it couldn’t be unlocked. Might require government intervention though.