http://unixetc.co.uk/2019/07/07/raspberry-pi-4-real-world-tests/
https://www.raspberrypi.org/forums/viewtopic.php?t=228727
https://lemariva.com/blog/2019/09/raspberry-pi-4b-preempt-rt-kernel-419y-performance-test
https://yosh.ke.mu/raspberry_pi_isolating_cores_in_linux_kernel
Install Raspberry Pi Imager to Raspberry Pi OS by running sudo apt install rpi-imager in a terminal window.
sudo raspi-config Enable booting to CLI and SSH server.
https://realpython.com/python-raspberry-pi/
https://www.thegeekpub.com/239681/setup-a-raspberry-pi-vpn-server/