It takes a couple pieces to get this working, but it'll totally be worth it.
Github Side
First, configure your workflow to be able to be triggered by an external event.
Then, create a Personal Access Token (PAT).
Github Action
Add a repository_dispatch with a corresponding event_type. You'll configure the event on the Coda side once you install the pack. All workflows with the same event_type can trigger from the same Coda Action!