I've deliberately avoided deep arrays for settings, so my jsonb settings merge is simply:

    SELECT COALESCE(companies.options, '{}'::jsonb) || COALESCE(groups.options, '{}'::jsonb) || COALESCE(users.options, '{}'::jsonb)
      FROM users
      JOIN companies ON users.company_id = companies.id
      LEFT JOIN groups ON users.group_id = groups.id
      WHERE users.id = ?

Where I need a hierarchy for key names I'm just prefixing.

I sit right on the knife edge of tossing all the jsonb options and replacing with an old-school normalized EAV model.