Instructions for generating certificates for MariaDB/ Postgres

Could someone help me figure out how to generate mkcert certificates the same way that this article does with OpenSSL?

https://www.cyberciti.biz/faq/how-to-setup-mariadb-ssl-and-secure-connections-from-clients/

I've tried to use mkcert for MariaDB server/client configuration but for some reason it doesn't work.

Start with the linked Cyberciti OpenSSL article and reproduce the reported mkcert setup for MariaDB and PostgreSQL server/client connections. The work is done when the repository documents working certificate-generation and configuration steps, including enough detail to explain why the current attempt fails.

Written by the indexing model from the issue text.