I didn't quite understand this. Presumably, you're developers and just created a I assume fairly complex backend product (better than Google Maps). What stopped even just one of you from picking up a book on react-native/electron/whatever and knocking out a workable front-end? Did you exceed your runway, run out of time etc?
edit: to clarify, I meant after the third-party didn't work out. Also not critiquing just genuinely curious