I just output an interactive 3D plot from Plotly as html file, and I saw blogs about embedding it in webspages and RMarkdown files, which got me wondering: Is it possible to embed it in a Markdown file? In particular, can I embed the html in the README.md of my Github repository? Should be cool.
If your HTML is simple HTML without any colors, font tags, CSS, or JavaScript, then yes, you can embed it, and it will probably work. However, for security, functionality, and accessibility reasons, GitHub filters out most colors, font tags, CSS, and JavaScript from the HTML that's rendered, no matter how it comes in.
So if your Plotly-generated HTML uses those features, then it won't work. You could embed it as an image if that's suitable for your needs.