Yes, your end users can message you and provide you feedback.
You have two options:
1. Typeform. You add a Typeform questionnaire to your lessons so they can answer questions and you can gather feedback from your customers.
2. You can also enter your contact email address within PassionApps under Setting - Other
When you are creating content, you can also add an Introduction product that contains all the important details before they start using your app including how to get in touch with you.