Just a note that DRH's doctorate was in computational linguistics. This is reflected on SQLite in the sense that the part he likes working on the most is the front-end as opposed to features like concurrency for example. So, i guess a deep dive into the topic is required.

What the above comments showed in terms of what is taught at unis seem to be great starting points. Since he already knew classical stack-based VMs from the start, this maybe shows he learnt it at uni. Would love to ask him about it!