After a few years using Google Cloud services, I have realized that the Google Cloud SQL service only allows working with MySQL, PostgreSQL and SQL Server, so it has come to my attention to know if it is due to any reason in Special, perhaps due to lack of agreements or simply Google has ignored the fact that many of us need to use MariaDB as a database engine in Google Cloud SQL.
Also, I would like to know if there is any other way to connect a Cloud SQL instance (that uses the MariaDB engine). In my case, I usually occupy Google Cloud Run by connecting a Cloud SQL instance.
In the image below, you can see the DB engines that Cloud SQL only accepts those DB engines. While it is true that, according to my research, MariaDB is a fork of MySQL and that this, in turn, is open source, perhaps there is no need to want to incorporate this database engine directly, however , the question remains the same, why? Working natively with Cloud SQL and MariaDB would be great, considering that you can get a lot out of MariaDB today.
My personal conclusion
Many people will surely ignore the fact of being able to arrive at a concrete answer, these types of questions are not asked in this community, perhaps they are, and perhaps some of them are accepted or voted negatively. Anyway, I think that the community should contribute a brainstorm commenting on their particular situations using these services and if they adapt to the needs of new technologies such as MariaDB.