I'm surprised to hear that archinstall doesn't start with setting the keyboard layout. I have only installed manually and IIRC the installation guide shows how to change the layout as the first step after booting into the installer.

Meanwhile in Finland my first exposure to a Unix shell was in an introductory IT course in uni, and that inspired me to switch to Linux four years ago. Without all of that I would have never got my current internship where 90% of my work is in the terminal.