It doesn't speak MariaDB (yet - I have a long-term goal to investigate adding alternative database backends as plugins) but you can instead use the https://datasette.io/tools/db-to-sqlite CLI tool to convert a PostgreSQL or MySQL (or other SQL Alchemy supported) database to SQLite, then use Datasette against the resulting file.
This actually works pretty well for small (<1GB) databases, where you can run a cron periodically to build the SQLite version.
I also often load data into Datasette and then do custom visualizations in Observable Notebooks by fetching data back out through the Datasette JSON API - here's an example notebook that does that, using the Observable Plot charting library: https://observablehq.com/@simonw/datasette-downloads-per-day...
This actually works pretty well for small (<1GB) databases, where you can run a cron periodically to build the SQLite version.
Then you can visualize with plugins such as https://datasette.io/plugins/datasette-cluster-map or https://datasette.io/plugins/datasette-vega
I also often load data into Datasette and then do custom visualizations in Observable Notebooks by fetching data back out through the Datasette JSON API - here's an example notebook that does that, using the Observable Plot charting library: https://observablehq.com/@simonw/datasette-downloads-per-day...