How it differs from a product page
A product page sells: it carries imagery, persuasion, reviews and a basket. A canonical record identifies: identifiers, the facts a buyer asks about, their sources, and what the record does not claim. A good product page can be a canonical record; most are not, because the facts live in scripts and the sources are not stated.
Example
The records at /products are canonical records in this sense: each lists its identifiers, each fact with the page it was read from, the day it was read and a digest of that page.