print or extend Python output to an HTML file

Sure, so DOM is the document object model. It is what makes up a website. Each "element" you see on a web page is one object on the document. See MDN DOM reference.

Python, as of now, is not understood by browsers. So placing python inside a script tag will not do anything. However, a tiny bit of javascript should do the trick.

To understand the next bit you have to understand that as part of GitHub pages, which you use to host, they host the whole repo. Using index as the standard "default" file. Example both vickilanger.com and vickilanger.com/index.html map to the same page. We can see that your python file is hosted at vickilanger.com/portfolio.py. This by default will try and download the file, and run it. We will use this to our advantage.

We can use the javascript fetch API, with MDN docs here to dynamically request your portfolio file and insert the text inside an element.

So first, we can remove the code from the HTML and add an ID label to the code block. We will use this later. We also supply some default text that will be displayed while the fetch is in progress.

<code class="language-python match-braces" id="portfolio-code">
  Fetching portfolio...
</code>

Then at the end of the body, we can add a script block with some javascript to dynamically updated it after the page is loaded.

<script>
  fetch("/portfolio.py")
    .then(response => {
      if(!response.ok) {
        throw new Error("Bad Response")
      }
      return response.text()
    })
    .then(text => document.getElementById("portfolio-code").innerText = text)
    .catch(errror => document.getElementById("portfolio-code").innerText = "Unable to fetch portfolio, try again later")
</script>

This will request your portfolio file. If the response failed it will raise an error. Parses the text, and updates the code block to the text of the file, using the code element we tagged with ID above. On any error, it displays an error message.

That should do it, I tested it locally but I used the full URL, you should be able to use the local path URL.