Contextual filter for an indirect taxonomy term?

I know how to display similarly tagged items of a different content type in a view block (here is a good explanation and settings picture).

I have a scenario where the term IDs aren’t directly associated with both content types. The term reference field on the page content type is attached, not to the view content type itself, but to another taxonomy that is attached to the view content type (the view content type uses a taxonomy that has a field which is also used in the page content type).

How can I filter my view to items that are “mapped to” the term?