> That's a lot of steps for something that would be a simple route rule or mangle + mark routing on mikrotik.
I'm sorry but suggesting buying and setting up hardware as an easier and more accessible alternative to a purely software-based solution that will take at most a couple of hours to install is simply ridiculous.
A mikrotik router can be purchased as low as $24.95 and it will not only provide you with an enterprise grade router, it will also provide you with the functionality I mentioned above.
The point of my comment was that it can be done at the router level, instead of requiring the user to run and maintain Pi-hole, Traefik, Gluetun, Nginx, and the server required to run these apps/containers.
The route rule would route out a VPN instead of the main route.
If the domain name resolves to many IPs you can keep an address list up to date using a simple script.