If you want to show the list of databases, you can use pg_database or pg_database_info table, which are included the standard PostgreSQL catalog tables.

SELECT * FROM pg_database;

select datname, datdba, datconnlimit from pg_database_info where datdba > 1;

pg_database_extended


References
System Catalog Table / Amazon Redshift Docs
https://docs.aws.amazon.com/redshift/latest/dg/c_intro_catalog_views.html
https://docs.aws.amazon.com/ja_jp/redshift/latest/dg/c_intro_catalog_views.html

System Catalogs

https://www.postgresql.org/docs/8/catalogs.html

https://www.postgresql.org/docs/8/catalog-pg-database.html