You have several options, so first you need to decide on your mobile strategy.
Do you want to build a native mobile app, a PWA, or a responsive/phone web navigation profile? Each choice comes with upsides and downsides and a different approach to your question.
Perhaps this link can give you some more information: https://www.mendix.com/mobile-architecture/
That depends. Do you want to have a native mobile app, a hybrid mobile app, or a mobile view of your web app?