I have read some literature on all three of my ideas, and was pleasantly surprised to see that there was a lot of academic research potential in the ideas that I thought were a little dry in research, which was my main concern with my ideas. The most exciting idea I got was adding a food recommendation system for my food ordering app, where the user can get either a healthy or a tasty recommendation depending on their preferences.
For my second idea, I realized I need to research the intersection of human-computer interaction and pedagogy.
For my third idea, there is a lot to research about indexing a large number of text documents, where the corpora grows, and there is a space constraint. I can also look into text summarization techniques and metadata extraction from the documents.