I think GOS is safer because it “re-lock the bootloader after installing”
It depends. Installing a custom Android distribution (or “custom ROM”) doesn’t require rooting devices which support the installation of alternative operating systems such as Pixel and Motorola devices. Other devices (like Samsung Galaxy) which prohibit alternative operating systems may require rooting to circumvent that restriction, but again it’s generally advised against for security reasons even for those devices.
Samsung A14 is a budget phone that’s not supported because it requires One UI Core 5.1 or higher. I’ll look into Private Space, but my Samsung phone doesn’t have sensitive data, so I’m good without it.