I recently wanted to install Arch Linux onto a second drive on my Windows desktop, but didn't have a flash drive around. Eventually, I figured out how to use Windows Subsystem for Linux (WSL) instead of the installation medium to install Arch Linux on my second drive with the GRUB boot loader. I could not find any information on how to do this, so I had to figure it out mostly on my own. I wrote this guide to help anyone who wishes to try this installation method too!
PowerShell (Administrator):
wsl --install