Is this available anywhere? Super interested
The most useful part is doing set intersection operations on JSON array's. Probably the second is extracting a value by path across both.
It's not crazy to implement, SQLite was the harder side. Just a bit of fiddling with `json_each`, EXISTS, and aggregate functions.
For some of the operations, the method I was using required marshaling the inputs to JSON before sending them over the wire. And that's nicer in a non SQL programming language. But both db's ultimately do have json_build_array/json_build_object for PostgreSQL or json_array/json_object for SQLite3.