Use sql

A doctor looks at an X-Ray of a robot and sees SQL inside

At its surface, Drupal seems to be a lot of CSS and Javascript being pushed around by lots and lots of PHP code -- these days with healthy chunks of Composer, Twig, and some other things.  Inside, though, at its core, is a SQL database.  (Usually -- but if your Drupal site isn't running SQL, you're probably not actually interested in simplifying Drupal.)

Taking a peek at the database tables inside of a Drupal site and you'll often see a simpler structure than you see on the outside.  Nodes, fields, taxonomy relationships -- it's amazing what you can learn with a few simple select statements.  (Want help writing them?  Ask ChatGPT, its happy to help.)

Have fun spelunking!