I've worked in Mongo enough to know that whatever decision I make will end up being wrong.

What i will never understand is why mongo doesn't have some simple means of document referencing that automatically updates documents a doc is embedded in. If it's such an important pattern that every app needs to reinvent for itself, just add it to the system.

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
    );