As long as your github page has https (it does) Cloudflare can do full HTTPS all the way through, and even strict to require a valid ssl cert (which github has).
[1]: https://konklone.com/post/github-pages-now-supports-https-so...
I acknoledged the issue given, but considered it better that the content the user is accessing was hidden for their privacy - the link between Cloudflare and GitHub is backbone-of the internet stuff and has a whole different set of risks. Would be nice to plug it.