A Mac is required to build to an actual device or Simulator. You'll definitely want that to test out any device specific differences.

You can count on the framework to abstract away big significant parts of your app (business logic, UI) but some of the nuances you will probably have to tweak yourself. Launcher icons, handling notches, device specific features, and other weird oddities.

At least in the React Native community, you can often get away with building to the device only once every native dependency change. This becomes a better experience with Expo though