That's a great question (and somewhat of a popular one). Here are a few posts with responses that discuss ESL content:

https://khanacademy.zendesk.com/hc/en-us/community/posts/202813110-ESL-Learning

https://khanacademy.zendesk.com/hc/en-us/community/posts/210874268-Khan-Academy-

If you have any particular suggestions for ESL and ELL courses (outline/structure, areas of emphasis, etc.) that you would like to share with the community and have Khan Academy consider, feel free to edit your post or make a comment with those ideas. We always enjoy hearing from the community!