Simple answer – it is not possible.
Long Answer – Gutenberg stores all the blocks of a page in one long serialized data field. There is no way (that I know of, or at lest yet) a way to identify and map fields to import or even export any type of data.
– The biggest advantage of Gutenberg is keeping the database size relatively very small as oppose to using Custom Fields – in fact the size differences between the two are astronomical.
– Because Gutenberg mixes content (data) and design, as we all knew previously not to do so until now, we cannot have front end forms, and complex search forms, searching data on multiple search criteria, like finding a house to buy, price being less than $i million, with at least 4 bedrooms, and a swimming pool. I dare ANYONE to show me how to do these 2 things with Gutenberg.
– Of course with Custom Fields, we can import/export data from let’s say a csv file, have front end forms, and even perform complex searches. The biggest disadvantage is that even with a modest sized website, your database is going to grow impressively big, and very fast.
