But seems unrelated to sharing library, or do I get meaning of this library wrong?

Tough discussion. I think it fits tbh. We already have some public sharing handling here.
Every app that uses the Guest nickname would be in a context of sharing (talk conversation share link, file/folder share link, poll.... etc

So I think this is where it makes more sense :)
Not to be confused with the guest app here ⚠️

Hm I am not that sure, as this library is more about files sharing (potentially we should add the Share model etc to this library).

For me this part should probably be in the same library as getCurrentUser so auth?

(code looks fine tough)

potentially we should add the Share model etc to this library

Our entire sharing backend allows any resources to be shared, not only file :)
Theoretically. So any sharing related thing wuold belong here I would say 🤔

Nonetheless, I would also agree, I like the idea to have this on auth.
Since we're a few that will use that one, I'll let you all decide 👀

Auth sounds even more fitting to me

Let's gooo! The people have spoken! 🧑‍⚖️

nextcloud-libraries/nextcloud-auth#666