We already support dynamic content via JSON: https://help.ortto.com/user/latest/campaigns/creating-a-new-campaign/email.html#dynamic-content - would this cover your use cases? Or is having it working as RSS important too?

We used this feature in Mailchimp to automate newsletters and other content within campaigns via Zapier RSS feeds. Would be an easy win.

This would be a fantastic feature to have.

Doubly so if it could go back and we could create a drip campaign that starts based on any specified post date.

I second that! Replicate Mailchimp's system, it looks very simple and effective :)