Interesting! I have a partially-built, related, tool, to extract "words" from e-books, so I could build flashcard lists and make sure I knew the majority of words that were used - most of them would be common words but every book has a decently-sized selection of specialised vocabulary. I did think about trying to get something fancy done with an LLM or an NLP for figuring out the separable verbs, but in the end, I took a very... brute-force approach, basically grabbing the final word in the "phrase", then prepending that to every word in the phrase one by one and asking "is this a known separable verb?" - I'm not sure how well it worked, but that's a different story.