opensource.com article on the virtues of CopperheadOS.
“Unlike other custom ROMs that strive to add lots of new
functionality, Copperhead runs a pretty vanilla version of AOSP. Also,
while the first thing you usually do when playing with a custom ROM is to
add root access to the device, not only does Copperhead prevent that, it
also requires that you have a device that has verified boot, so there’s no
unlocking the bootloader. This is to prevent malicious code from getting
access to the handset.”