Before building something, did you test your idea ? Life's too short to build something nobody wants ;)
You can use clarity, sohelpful.me to conduct some interviews, build a landing page with quickmvp.com, unbounce or launchrock to validate that you solve a real problem. Then when your idea is validated, your can build a MVP (Minimum viable product) that might be for example a website (imho faster and easier to build than an app) to test your assumptions. Then if early adopters need functionnalities that really need to run as an app, you can provide them on pc, tablet or smartphone using your core web backoffice.
If you want to discuss with me, feel free to have a free call here https://clarity.fm/laurentroger/white665 or here http://www.sohelpful.me/laurentroger