I can't wait to get access to ChatGPT with voice so I can practice my Spanish. I suspect that the utility of vanilla ChatGPT for language learning will soon obviate the need for any custom apps.
I've been thinking about a layer on top of these chat apps that augment the experience for learning in particular. I've found that once you dig into the problem, a key element to solve for is reinforcement. The "provide information" part is easy, now how do you make it stick and how do you continue over an extended period of time?