It’s genuinely interesting to hear the thought process behind it, and it sounds like you have some passion for this kind of project.
Keep exploring and see where it takes you!
As an aside my parsing of the https://kaikki.org/dictionary/English/index.html data has 64405 7-letter words – I dropped proper nouns and slang to the best of my ability. You can download the word list (sans definition / word type) here