I've looked into using educative.io for course creation. There is a little bit more of politics involved when creating the course because of the expectation of high quality code. Also they use internal Docker tools to be able to create the interactive coding environments.

Slip, which I am using right now, is more straightforward and the ability to have code snippets in line which flows with the material is awesome.

Also, Slip is working on integrating with multiple platforms (StackBlitz, Figma, Repl, CodeSandbox) so we can leverage those platforms as well.

Both have a great offering and creating a course is "free" so would recommend giving both a try if you're looking to create a course.