How to add to my GitHub page an html page which comes from another repository of mine?

I created a GitHub page following the instructions and it is published under GitHub Pages as example.github.io.

Now I would like to add to this page the HTML pages of my projects, which are stored in other repositories different from the one where the page is stored. For example, I would like to add my_project.html which is stored in my_repo.

To this aim, I would prefer

not to add the projects to GitHub Pages as suggested in this answer or here
not to clone the whole project repository in the GitHub page repository as suggested here
not to use the htmlpreview.github.io/
not to copy-paste the HTML file into the example.github.io repository (because if I update the project, it will not be updated on example.github.io)

Is there a way to, for example, clone the single html file my_project.html from the my_repo repository to the example.github.io one?

Or to directly link to the HTML page?

Please, notice also that I am relatively new to GitHub and I use it through the browser interface.

I already made all the naive attempts like adding a link to https://example.github.io/my_user/my_repo/blob/main/my_project.html, to https://example.github.io/my_user/my_repo/my_project.html, etc., but I am well aware they will not work if the html file I want is not contained in the same repository as the index.html.

Solution

You can use GitHub Actions to deploy your project to GitHub Pages, and download the files with a script before deploying the project :

workflow.yml :

jobs:
  deploy:
    # Grant GITHUB_TOKEN the permissions required to make a Pages deployment
    permissions:
      pages: write      # to deploy to Pages
      id-token: write   # to verify the deployment originates from an appropriate source

# Deploy to the github-pages environment
environment:
  name: github-pages
  url: ${{ steps.deployment.outputs.page_url }}

# Specify runner + deployment step
runs-on: ubuntu-latest
steps:

  - uses: actions/checkout@v4

  - name: Download files
    run: |
         wget https://github.com/paolosaracco/MTG-TopRankedDecks/blob/81498093c5b6d3cfd1c6767f34d98902a9f2488b/MtG_project.html
         wget https://github.com/paolosaracco/MTG-TopRankedDecks/blob/*************/MtG_project.html
         # etc
         
  - name: Upload pages artifact
    uses: actions/upload-pages-artifact@v3
    with:
      path: / # Where all the static files are located

  - name: Deploy to GitHub Pages
    id: deployment
    uses: actions/deploy-pages@v4

You can find more documentation here to deploy with a workflow : https://docs.github.com/en/pages/getting-started-with-github-pages/configuring-a-publishing-source-for-your-github-pages-site#publishing-with-a-custom-github-actions-workflow