How to install the aarch64 toolchain for armv8 cortex-a53 on Debian?

As of Ubuntu 18.04 you can do:

sudo apt-get install gcc-aarch64-linux-gnu
aarch64-linux-gnu-gcc -mcpu=cortex-a53 hello_world.c

The package gcc-aarch64-linux-gnu is at version 4:7.3.0-3ubuntu2

However, for Raspberry Pi, you should just download the official binaries from https://github.com/raspberrypi/tools which is the more reliable way to do it as explained at: https://raspberrypi.stackexchange.com/questions/64273/installing-raspberry-pi-cross-compiler/83215#83215

Finally, for bare metal, I was not able to find the analogue of arm-none-eabi-gcc, I wonder why: https://github.com/cirosantilli/cirosantilli.github.io/issues/68