Hello,
Have you set up either one yet?
If not, then you should set up web version first as it would speed up the testing process.
I have set up Google and Github authentications recently and also, its a web app plus a mobile app.
The main process remains the same for both the versions as it has nothing to do with what platform you are on as long as the implementation is well written.
Have a look at this doc, if you haven’t already.
I am a beginner in this server related stuff and I was able to achieve it with about a week of tinkering with it.
It should take you much lesser time if you know what you are doing.
Thanks.