This is creepy as fuck - I don't see why I would ever want any local app, let alone a third-party, taking guesses at my mental state. What sort of use-cases did you build this for?
As for use-cases, there are plenty - and some not as direct as others but particularly within healthcare and life sciences there are plenty of uses around efficacy tracking and making sure interventions and treatments can be delivered appropriately based on objective assessment. The latter use leads into the problem many companies delivering health care interventions have with survey fatigue and subjective data bias.