Wildcard sub subdomin on github.io

Question

GitHub pages gives every user a subdomain such as https://user.github.io.
A project can also be hosted on a sub-path such as https://user.github.io/project.
I wonder is it possible to have a sub subdomain on the github.io domain such as the form of https://project.user.github.io?.
I am not looking for how to configure self-owned custom domains.

Answer 1

Not possible. You will need your own domain if you want something else.