As a middle ground, we could implement a solution for the bottom tier: small to medium sites and blogs. These sites don’t necessarily need a full-fledged MySQL database.

SQLite seems to be the perfect fit:

• It is the most widely used database worldwide
• It is cross-platform and can run on any device
• It is included by default on all PHP installations (unless explicitly disabled)
• WordPress’s minimum requirements would be a simple PHP server, without the need for a separate database server.
• SQLite support enables lower hosting costs, decreases energy consumption, and lowers performance costs on lower-end servers.

What would the benefits of SQLite be?

Officially supporting SQLite in WordPress could have many benefits. Some notable ones would include:

• Increased performance on lower-end servers and environments.
• Potential for WordPress growth in markets where we did not have access due to the system’s requirements.
• Potential for growth in the hosting market using installation “scenarios”.
• Reduced energy consumption – increased sustainability for the WordPress project.
• Further WordPress’s mission to “democratize publishing” for everyone.
• Easier to contribute to WordPress – download the files and run the built-in PHP server without any other setup required.
• Easier to use automated tests suite.
• Sites can be “portable” and self-contained.

Source and other links:

• https://make.wordpress.org/core/2022/09/12/lets-make-wordpress-officially-support-sqlite/
• https://make.wordpress.org/performance/roadmap-2023/#category-database-optimization
• https://wordpress.org/plugins/sqlite-database-integration/