Base OS

DietPi

SSH

DietPi uses Dropbear ssh

mkdir ~/.ssh

# Set permissions. Very important for ssh to work
chmod 700 ~/.ssh
chmod 600 authorized_keys

# restart ssh
sudo systemctl restart dropbear

Disable password auth

# add -s as argument
sudo sed -i '/^DROPBEAR_EXTRA_ARGS=/s/"$/ -s"/' /etc/default/dropbear

## restart ssh

mDNS

apt install avahi-daemon

This will setup a default as <hostname>.local