"body" is the "json in its own column" you're asking for. They are doing exactly what you're saying.
The point is exactly that it means you can selectively retrospectively add virtual columns, optionally backed with an index, as you decide which fields you need more structured access to.
The example you're giving is in principle the same as the "ALTER TABLE ... GENERATED ALWAYS AS ... VIRTUAL" example + a subsequent index in the Sqlite example.
Comments
"body" is the "json in its own column" you're asking for. They are doing exactly what you're saying.
The point is exactly that it means you can selectively retrospectively add virtual columns, optionally backed with an index, as you decide which fields you need more structured access to.
The example you're giving is in principle the same as the "ALTER TABLE ... GENERATED ALWAYS AS ... VIRTUAL" example + a subsequent index in the Sqlite example.