You don't need to involve a route, you can use the service name directly to connect to it. The only caveat on that is that you need to (as admin), set up a pod network between the two projects. This is better as creating a route means it will also be exposed outside of the OpenShift cluster and so publicly accessible. You do not want that if these are internal services that you don't want exposed.

For details on pod networks see:

• https://docs.openshift.com/container-platform/latest/admin_guide/managing_networking.html#admin-guide-pod-network