How to contribute to File Application and add MFA verification in folder management?

Hi all
I am trying to add a feature to the NextCloud File Application to be able to share a folder just for users who logged in using MFA. I guess I should add a flag that indicates the folder is forced on MFA and in session I need to determine the MFA status of the user. I also realized that the files and folder list are coming from the DAV service of the NextCloud and I should modify that part of the code additionally.
I know about the concepts and steps but I have no idea about the development phase and I think I need to learn more about the Infrastructure of DAV and File management in NextCloud and the development guidelines and standard inside it. Is there Anybody to provide such data and help me to achieve the goal?