Defining a catch-all route in routes.yaml

How do I create a route in routes.yaml that handles everything starting with a particular url prefix?

I would like to have one page, /churches, that not only handles /churches, but all urls starting with that, like /churches/1/church-name.

The important point about this page is that its content is rendered by the API of another system. In churches.hbs I have a snippet of javascript from this other system that reads the whole url, then goes and renders it.

I tried things like this in routes.yaml, but no joy:

    /churches/*: churches
    /churches/{slug}/: churches