There's no GUI-based way to iterate over a repeating field in a routing rule, but you can create a custom function that will be available from the drop-down Function list in the expression editor. That can iterate over the repeating field and return whatever value you're looking to test against.

This is hilarious! I started to add that exact feature last night but got interrupted by the dog's apparently dire need to go outside ... and that need cannot go unaddressed without unfortunate consequences.

I saw the notification of your update this morning, before I got back to work.

Again, thank you!