Commuters in specific regions often need information that general navigation apps don't surface well - like local transit quirks, schedule nuances, or fare policies.
Build focused apps that deeply understand one city's transit system, with features like offline schedules, service alerts, and fare calculators.
Charge upfront or offer premium features like multimodal trip planning.
Start with one city where you have personal transit experience.
Risk of being out-featured by large mapping platforms.