Can I define multiple routes sending traffic to the same app?

Yes, multiple routes can send traffic to the same app.

As long as the route's upstream key points to the app's unique name in your .platform/routes.yaml file, traffic will be routed to it when the route is matched, regardless of other routes' configurations.

For more information on this feature, please see the following page in the Upsun documentation:

https://docs.platform.sh/create-apps/multi-app.html#routes