We've seen a convergence of document DBs adding relational features, and relational DBs adding document features.

I had such a bad experience with Mongo DB that I will absolutely never use it again, and will never recommend that anyone else use it either.

This alone will get you 90% of the benefits of Mongo DB but with the full power of Postgres for everything else:

    create table document (
        id uuid primary key default gen_random_uuid(),
        doc jsonb not null
    );