Can the user page and project page of git - coding page use the same custom domain name? If so, how to do it? Thanks!

Question

For example, assuming my personalized domain name is mydomain.com
I want:

http://mydomain.com  可以访问用户page

There is a project page, the project name is proj

http://mydomain.com/proj  可以访问项目page proj

Github pages can meet the above requirements