Is creating an AuraDB Free Instance possible via GCP marketplace ?

Currently, creating an AuraDB Free Instance (also referred to as Free tier) is only possible when you log in directly (not via a GCP project - also known as punch-out ) to the Aura Console.

If you attempt to do so via GCP (see the top right corner), you will be presented with different instance sizes for paid instances (Pro Tier), and the Free tier option won't be available. 

Unfortunately, this is currently not designed to be available.

Instead, please log in to the Aura Console directly, and you will be able to create the instance (but it will not be visible nor associated with any GCP projects).