Honestly, if y’all would help your friend out with Linux they might be interested. If you just write down a note for them with the most basic commands for Debian, they would be okay.
DE: Use GNOME
Partiton layout: Use default /home for everything, don’t make seperate partitions for /root, /var, etc.
Add their user(s) to the sudoers file
CTRL+ALT+T to open the command line
Basic commands:
sudo apt-get update
sudo apt-get upgrade
Install Flatpak, and bookmark Flathub in their browser. That should be good enough and honestly anyone could figure this out.