Using Mullvad VPN on Qubes OS | PrivSec - A practical approach to Privacy and Security
This is my setup for Mullvad VPN on Qubes 4.2. It differs from solene's guide in that it uses systemd path to trigger /usr/lib/qubes/qubes-setup-dnat-to-ns. No rc.local (which is legacy stuff and shouldn't be used anymore) required.
You can also create multiple Mullvad ProxyVMs from a single template instead of needing to use standalone VMs.