Thousand of unstructured data types and options are present that can be used on a web page. ProductOntology.org can be used to extend Schema.org structured data to incorporate virtually anything that’s described in Wikipedia.
Recommendations: Googles Unconfirmed Search Ranking Update Is Significant
Mueller Replied on it:
Visible Rich Results
Unsupported Structured Data is used and described in Google’s developer pages then rich results will not be visible.
The use of unstructured data which doesn’t result in a rich result will help Google to understand page entities better.
Why it is relevant?
It is just about entities on your page, it will not boost the ranking, as said by the Mueller. It will only clarify what the page is about.
The more clarified answer of Mueller is shown in the video below:
Unsupported Structured Data May Be Used By Google
Video Source: Youtube