Migrating from PGSQL to MariaDB based environment

Do you already have a workbench installed locally?
If not, you can install a workbench:
https://data36.com/install-sql-workbench-postgresql/
then use a migration tool to convert:
https://www.dbsofts.com/articles/postgresql_to_mariadb/

Once you have your file dumped from Postgres, you could load up phpMyAdmin for Maria on your host and import it.

You’ll need to update your wp-config.php file with your new connection strings:

Editing wp-config.php

Note that this is not a WordPress support question.

Well, it’s actually WP related since the intention was to not lose the content already generated.

However, I was able to achieve that goal by using native WP export/import tools.

Regards.