Denis Magda is a database developer-advocate (formerly at Yugabyte and Apache Ignite) and one of the more visible independent voices on the case for using PostgreSQL as a default-choice database for everything — replacing the application stack's typical mix of cache + queue + search engine + RDBMS with one well-tuned Postgres instance.
His CourseFlix listing carries Just Use Postgres!. Material is paid and aimed at engineers and architects making the database-choice decision for new applications.