All of Google's own devices have an unlockable bootloader and you're free to install your own operating system (both on smartphones and chromebooks). That bein

All of Google's own devices have an unlockable bootloader and you're free to install your own operating system (both on smartphones and chromebooks). That being said, rooting is a security hole - the PIN lock on most rooted phones can be trivially bypassed, and an application running as root can persistently and invisibly compromise the system (and bypass safeguards on things like Android Pay). The only non-Google Android fork which does not trivially compromise device security was Copperhead OS (now defunct) - they would ship devices with a locked bootloader and sign their updates, achieving a similar level of security (assuming a secure build system).