I don’t think you should do LLM or machine learning stuff if you want to get software development out of the project. Mostly because most of the time you won’t do software dev stuff with that kind of stuff. You will mostly just download some off the shelf model, prepare data, tweak parameters, cross your fingers and pray for slightly better results, and repeat.

My recommendation without knowing much about you is to make a game engine. You remove the pressure of making something practical, and can just focus on making stuff that looks cool. You can easily control the scope of the project, and you will face a great variety of software development challenges. Lots of opportunities to learn.

And finally you will also have something that’s fun to present.