How to add comments in blog posts on GitHub-pages websites

I've made a website based on GitHub pages using Jekyll Theme. Currently I can post blogs in that website as well. However, I want to add a comments section at the end of the blog posts.

There are tutorials on how to add comments sections using Disqus. But I think that to use Disqus one needs to have a paid subscription. So I am looking for an alternative to Disqus to add a comments section.

Sharing any idea about it will be appreciated.

_{Originally from @Encipher here: (now-deleted for being "off-topic" on Stack Overflow since Stack Overflow requires the question to contain programming in it):}

Here is what this well-received Q&A used to look like on Stack Overflow: https://web.archive.org/web/20220506172751/https://stackoverflow.com/questions/59096243/adding-comments-in-blog-posts-on-github-pages

There were 18 upvotes on the question and 20 on the main answer. I simply want it to be publicly searchable again.