While submitting the final self made project in the documented form to the Hackster site do I need to also mention the core coding in the document of the project?
Yes, you can mention but it should be human readable. It means that the code should have short comments to explain the steps. You can refer to this link as a specimen- https://www.hackster.io/AlexWulff/how-to-create-a-high-quality-project-tutorial-e25feb