The guide is based on debian13-minimal, but it should work on debian-13-xfce or debian-13.

Prepare the template

Start "Terminal Xfce" in dom0
Run qvm-template install debian-13-minimal
Run qvm-clone debian-13-minimal debian-13-minimal-openvpn

> ℹ️ The following steps are required to install packages in the new template, as it's a minimal template, you can't use sudo from a regular terminal.

Run "Terminal Xfce" in dom0
Run qvm-run -u root debian-13-minimal-openvpn xterm
Run this command in the terminal that opened: apt install -y qubes-core-agent-networking qubes-core-agent-network-manager network-manager-openvpn-gnome
Run this command in the terminal that opened: adduser user netdev
Shutdown debian-13-minimal-openvpn qube

> ℹ️ The following steps will create an AppVM qube that will connect to the OpenVPN server and be used as a NetVM for other qubes.

Start "Terminal Xfce" in dom0
Run qvm-create --property provides_network=true --template debian-13-minimal-openvpn --label red --property maxmem=512 sys-vpn-openvpn
Run qvm-service --enable sys-vpn-openvpn network-manager true

Copy the OpenVPN configuration file to sys-vpn-openvpn

Move the OpenVPN configuration (unzip the file before if needed, the appvm does not have the tools to unzip) to the qube sys-vpn-openvpn you just created.

This can be done by right-clicking on the downloaded file in the file explorer of the Qube that downloaded the configuration file, and choose "Move to other qube..." menu entry in the contextual menu.

Import the configuration file in sys-vpn-openvpn

Start "Terminal Xfce" in dom0
Run qvm-run -u root sys-vpn-openvpn xterm
On the network systray icon, left click, then hover on "VPN Connections" then click on "Add a VPN connection..."

vpn|420x141

On the shown menu, click on "OpenVPN" and select "Imported a saved VPN configuration..." instead
Click on "Create..."
Select the configuration file you sent to the qube, it's under /home/user/QubesIncoming/...
When prompted with "Choose new password for keyring" click on "Continue", you can fill the password fields if you want to add a password to unlock the VPN password but this is useless for most users as the qube is dedicated for the VPN task. You will be asked if you really don't want to use a password, click "Continue"
Fill the values for the fields User name and Password
Click on "Save"

Autoconnect

> ℹ️ For some reasons that still need to be understood, network manager does not offer to auto connect the VPN connection on boot. Trying to use `autoconnect.secondaries" on eth0 did not work either.