Genshin Impact: Obtaining the Nanocore from the Start

[Mainly follows the Sumeru storyline]

The otherworldly boy Qiu Yebai obtains the power of another world, the Nanocore, by accident while transmigrating. After spending time with the people of Liyue, he makes his way to Sumeru...

After crossing five hundred years of time and returning to Sumeru, what will Qiu Yebai do? What is the Nanocore's power really for? And what is the price of that power?