> Then republish your articles on other platforms like Medium, Substack and use canonical links so the search engines know your website is the source of the article.

I love the spirit behind this idea, but please know that Substack doesn't allow to set canonical urls on posts. This means that all content published outside of Substack will be considered a duplicate for SEO purposes unless Substack is set as the original source (which is the opposite of the suggested idea here).