How to obtain all existing topics and relations info

Hi,

I’m trying to find out how the following webpage manages to display its content querying Github API:

I’ve checked the REST API but it looks that queries applying only to one specific topic can be executed (with qualifiers if required): based on reference docs about search-topics

But I can’t obtain info about all existing topics, or even categories of topics as the gitlogs web page lists. There seem to be also a relationship (“Related Topics”) between topics that I should be able to query about:

Thanks

I even considered retrieving every user and their repositories extracting every topic for every repository. But GitHub doesn’t allow reading all existing users:
https://api.github.com/search/users?q=type:org

Downloads only 30 of a total of 4070467. And If I try to visit every page of users I get:
{
“message”: “Only the first 1000 search results are available”,
“documentation_url”: “Search - GitHub Docs
}

Found this: