Add new user on Ubuntu Server

Change the Default Home Directory

Edit /etc/adduser.conf

DHOME=/home2

Then, add new user

sudo adduser NEW_USER

Add New User to group

Add user to sudo group

sudo usermod -aG sudo NEW_USER

Add user to docker group

sudo usermod -aG docker NEW_USER

Hide New User from Login Screen

Edit /var/lib/AccountsService/users/NEW_User

[User]
SystemAccount=true

Then, restart account service and display manager

# Restart account service
sudo service accounts-daemon restart

# For GDM (default in modern Ubuntu)
sudo systemctl restart gdm3.service

# For LightDM (used in some Ubuntu flavors)
sudo systemctl restart lightdm.service

Reference

• How to hide users from the GDM login screen?