create a username.github.io page using vitepress
To have your own vitepress blog running on username.github.io in no time, follow these easy steps:
Create a new repo 
Inside your own github account, create a new repo called username.github.io where username is your actual github username. This is important, since otherwise repos page wont be deployed to the root folder of the username.github.io subdomain.
Create your vitepress blog 
Follow vitepress' getting started guide and set up your vitepress project
Change the build command 
In your package.json file, change
"build": "vitepress build",to
"build": "vitepress build --outDir _site",This is required for the deployment action to work.
Create the workflow file 
Create a new file in your repo called .github/workflows/main.yml and paste the contents of this file into it.
It's based on github's basic jekyll workflow, but instead of building a jekyll site, it builds and deployes a vitepress site.
Change your repo settings 
In your username.github.io repo, go to Settings -> Pages and set the Source to Github Actions. Then click Save.
Push your changes 
Push your changes to github and wait for the action to finish. After that, your vitepress blog should be available at username.github.io.
Final words 
The workflow will work for any nodeish static site generator, the important bit is the call to npm run build and that the output is generated into in the _site folder.