How are you?
Your question have too many possible answers.
Maybe you could start following the PWA topics: https://community.magento.com/t5/PWA-Theming-Layout-Design/bd-p/magento-2-theming
You can check out Progressive Web apps instead of building native apps. With Progressive Web Apps, you get some astounding features like push notifications, offline mode and faster page loading. PWA launches and works exactly like a native app and they take you less time, money and effort to build.
We at MageCube, have built an extension that can easily convert your Magento Store into a Progressive Web App. We would love to discuss with you on how we can assist your business in implementing a Progressive Web App.
Thanks and Regards
- MageCube Team