Curious, why Mandarin only? Is there something about the language that makes it more feasible or more attractive to the business?. FWIW I would consider using something like this if it could teach Japanese.
Mandarin is just first for us because:
1. Thomas was already learning it
2. We can talk to users in English
3. We have some native-speaking friends who helped early
4. Has excellent support in AI products (second only to English)