Unfortunately, Sensei do not offer such thing. However, as a workaround, you can enable comments on your lessons to allow student discussions. To enables learners to comment on lessons for courses they are enrolled in go to Sensei LMS > Settings > Lessons > Allow Comments for Lessons. Only registered learners can view these comments.
If you’d like to enable comments in Learning Mode, you must first add the ‘Post Comments Form’ block in the Site Editor for the lesson template.