This tweet explains in a concise way how to think about testing. You will get the most benefit from having integration and e2e tests. Unit tests are fine, but they will not give you as much confidence that your application is working as integration tests do.
Unit testing, as the naming already reveals is a type of testing where units of an application are being tested in isolation. You should write unit tests for shared components and functions that are used throughout the entire application as they might be used in different scenarios which might be difficult to reproduce in integration tests.
Integration testing is a method of testing multiple parts of an application at once. Most of your tests should be integration tests, as these will give you the most benefits and confidence for your invested effort. Unit tests on their own don't guarantee that your app will work even if those tests pass, because the relationship between the units might be wrong. You should test different features with integration tests.