I'm building a language learning app for intermediate language learners.
I'm learning Swedish and I found out that there are not many intermediate to advanced resources. Most language learning apps focus on beginners (rightly so, that's where the money is) so I built this first for me, but now I also have a paying users and people seem to like it.
Some new features I'm planning are SRS integration and pronunciation training with the "shadowing" technique.
Challenges: focusing too much on trying out new tech and finding a fair price point (still figuring this out)