Hi Leung Doug,
The same steps must work for Javascript as well. You will need to remove the type declarations (e.g. React.FC) and the non-null assertion operators (!), and use *.js and *.jsx file extensions.
apple-sign-in-button is certainly a react component that you can render in your login page. apple-sign-in only contains a function: place it where it better suits you. In my case that is in a redux action file, but you can have it inside loginScreen.js.
And yes, the Apple guidelines state that for them to approve your app, you must offer Apple sign-in when you use other third-party authentication options.
Cheers