I'm trying to get the data of the user's impact.
Therefore I used the /2.2/me route and did not found any of this data.
Is there any other route that gives this information?
I'm also missing the information about the Twitter name or GitHub name that are visible on the user account.
No, those fields are not exposed on the user object. They are not in SEDE either, according to the schema. I think those fields have been added after the API was created, and they simply didn't bother to update.
The alternative, if you keep the number of requests low, is to scrape each user's profile page. Take care that anonymous requests open user profiles by default on the Profile tab, instead of the Activity tab which is opened when you view your own profile.
