PostgreSQL Database 'Information' Script - is there one out there?

Hi,

Does anyone know of any existing script/s out there somewhere that
generates some kind of database/instance inventory, like listing of what
databases exist (\l), schema (\dn) in each databases, extensions (\dx),
user lists (\du), replication slots, tables, views, parameter
default/non-default settings etc?
Maybe there is already one out there, either a shell script or a SQL script
that I can just run from psql and save the output to file.
At the moment, running manually via psql running \l, running \c to each DB
and running \dn, didn't realize I have to run \dn on each database :(, and
running select statements from pg_tables and so on.