To be fair, for "anything over 5 years old" you can probably find a privilege escalation exploit.
wandering the web to find an exploit is way beyond my spare time.
iiuc the OG Verizon Pixel has an unlockable bootloader, but the operating system doesn't let you unlock it, meaning root access should allow unlocking the bootloader.
some devices have a legitimately locked bootloader, which means you're SOL.