Geth codebase question after the merge

Hello, I’m making an attempt to find out how Ethereum works by going by its consumer codebase, beginning with Geth – to date I’m very confused.

By combining the readings of ethereum.org, I now come to know geth is just execution consumer. Then am I appropriate to say {that a} huge a part of the code in Geth repository could possibly be cleaned up? And if not, why?

Additionally: any assist or firm to check codebases collectively is far appreciated!