To save product reviews from a product page, you can use the template Send a Slack message when a Shop review is published with the tag "buyer_experience".
This template sends a Slack message when a Shop review is published, which can be modified to save the reviews instead.
Alternatively, you can use the productCreate and productCreateMedia mutations from the send-admin-api-mutations.json document to create a product and add media (such as reviews) to it.
However, the provided documents do not contain a direct template for saving product reviews. You may need to create a custom workflow using the available templates and mutations.