For starters, we wouldn’t want to make a mobile app but instead what is called a “progressive web app.” (PWA) These are “apps” that are technically websites that have most of the capabilities of an app; because they are websites, you can go seamlessly from using them on a smartphone to using them on a desktop and they are much cheaper to maintain because they are just one codebase instead of three (one for website, one for IOS mobile app, and one for android mobile app). Whenever you see a website you visit on a desktop asking for your location or the ability to send you notifications, then you are probably dealing with a progressive web app (because it's tapping into those features that would be found on a smartphone).