Is there a way to push content/actions/activities from Marekto to Dynamics?
This should be moved to Products (Move link at the right). This isn't a support space.
There is no direct way to do so.
With some harder work, you can add the information you want to a synchronized long test field, in a JSON format, then use some workflow logic in MSD to decode the JSON and create the object you want.
It will be one way (fro Marketo to MSD) though.
You might want to look into third party solutions such as Bedrock data Sync that complement the standard connector.
-Greg