It’s literally inferior security wise. The desktop Linux security model is antiquated when compared to the advances in security/isolation/etc that modern mobile phone OSs have developed.
It's in a different league as it's a linux phone first and foremost, not degoogled/hardened android, you get full root access as a checkbox in settings that will install terminal app for you to hack to your heart's content, user having root access is not an attack vector for them
I was not asking about having terminal and root access. I was asking about security-wise parity, for example memory protection, full "disk" encryption, permission model, application sandboxing etc. This is the main selling point of GrapheneOS. This and Android application compatibility, but Sailfish OS has its Android compatibility layer too.