ESQL should support parsing JSON or KV from a string into separate columns. This is a high hanging fruit since it breaks the assumption of the query planner knowing the shape of the table at any point.

Example:

Expand into multiple columns, with an optional prefix:

ROW json_field "{\"foo\":\"bar\"}" | JSON json_field "json_parsed_" | KEEP json_parsed_foo 

Expand into a single column holding a special "JSON" type:

ROW json_field "{\"foo\":\"bar\"}" | JSON json_field | EVAL foo = JSON_PATH(json_field, "foo") | KEEP foo 

In this case, the JSON_PATH function would allow to extract stuff from a column with the "json" type