In contrast, I don't know that much about VMs.

But if you're making a big fundamental change to a system, I do know that it shouldn't start with a single "+279,276 -4,272" PR. It starts with a small patch with the core of the change so that everyone can understand what it does and how it works. (I mean, ideally, a change like this starts with documentation, discussion, diagrams, surveys of existing implementations, etc, before you start writing code)

You don't cram everything into a single 270K line PR, even (especially) with an LLM, unless you specifically don't want anyone else to look too closely at what you did.