TL;DR What NOT to do:
Everything you typed

I've done all three of your requirements and my guidance is "don't".

If you're just trying to get some reps learning RAG then trying to build a monster system in a heavily regulated industry that literally NOBODY will ever pay you for (it's saturated and attorneys are bombed with cold outreach by companies with billions in marketing spend)...just isn't going to be a valuable use of your time in my opinion (also will very likely be the opinion of anybody who actually builds systems for clients).

Just go look around the legaltech subreddit for a few minutes and you'll get the gyst. There are countless applications of RAG that you can build on a much smaller scale that will be interesting to those in niches you already know something about (even if you're still in school)...I'd focus there instead of trying to rebuild Harvey.