I tried to check Sandeep Panda AMA he has mentioned he ll write but not able to find full architecture post but lot of module base posts are available.
May be Sandeep Panda we need a feature to filter out post by you(user) in your(their) profile page.
From my understanding I will reply this.
Does it deploy the code on subdomain?
Does it deploy the code on users custom domain?
For both questions the answer may be NO. All the domains will be configured to the same Hashnode servers. So whenever a post of our custom domains (say heyvp7.tech) or hashnode sub domain (heyvp7.hashnode.com) is visited, then hashnode servers will be check which users post is checked and then which post is looked.
And all the best for job search, will ping you if I come across any post.