WordPress and “Oracle MySQL vs MariaDB”

WordPress usage stats: https://wordpress.org/about/stats/
Technically, 10.x versions are MariaDB

WordPress requirements: PHP 5.6.20+ and MySQL 5.0+
WordPress recommendations: MySQL 5.7+ or MariaDB 10.2+

Mysql: release history, downloads: stable, archive

MariaDB: release history 1, 2, downloads: stable
changelogs: 10.6

Compatibility: https://mariadb.com/kb/en/mariadb-vs-mysql-compatibility/

Differences I met

MariaDB doesn’t support ->> -> operators (issue)
Use their regular equivalents JSON_EXTRACT/UNQUOTE (docs) instead.
About JSON in MariaDB: https://mariadb.com/kb/en/json-data-type/

MariaDB syntax of generated columns is a bit different (it doesn’t have NULL / NOT NULL part).
Docs: mysql, mariadb