"Serious" Project Management in Coda? (Work Breakdown Structures)

I’m trying to do this by combining several templates to start with in the discussion below. Please contribute to the discussion if you have any thoughts! or maybe creative ideas! For example, has anyone tried to do a deep flexible hierarchy in apps that do allow it, like Smartsheet or Wrike and then synced data to Coda via Zapier - in order to “terraform” the hierarchy/template in Coda and then modify with additional Coda features? Any issues with that?