Best Tutorial i found back then.
micahflee.com
He is explaining for mullvad but since OpenVPN is used, u can use any provider which is OpenVPN compatible.
You tunnel the hole VM trough VPN, and setting a firewall, you can be 100% sure no IP can be leaked by nature.
Using Mullvad VPN in Qubes
A friend wanted my help configuring Mullvad VPN on their Qubes computer. Instead of just helping them, I decided to write a quick blog post explaining how I normally set up VPNs in Qubes. There are many different ways -- Mullvad even has its own Qubes guide -- but I
micahflee.com
You tunnel the hole VM trough VPN, and setting a firewall, you can be 100% sure no IP can be leaked by nature.