What are the minimum requirements or steps you need to complete in order for Google to index the site on Github pages?

Question

Google

Well, in fact, everything is in the title: the minimum program for a search robot to come!? An additional question is only: will the relevance be affected by the fact that the site is located on a 3rd level domain (the one provided by Github) and it is desirable to buy a domain or is it not important!?

Answer 1

In order for the bot to come, you either need to directly tell Google about the existence of your site, or place a link on some indexed resource (that is, almost any) and just wait.
It is important that your content is interesting and unique, well-designed in a digestible way. In short, think of your readers first, that's what SEO is all about. The rest (which is not important to readers) is not reliable.