Challenges can also be embedded via iFrame just like code editor.
You can see a quick demo in action here https://onecompiler.github.io/editor-embed-demo/challenges.html

<iframe 
  frameBorder="0" 
  height="700px" 
  width="100%"
  src="https://onecompiler.com/embed/challenges/3w7dby3mt/beginners-coding-challenge"
></iframe>

More options via query parameters

Query ParameterDescription
theme=darkLoad challenge in Dark Theme
hideLanguageSelection=trueDisable the Language switch button
hideNew=trueDisable the Language switch button