generate dynamic child in sticky header widget

if the API data is in this format then how would I generate sticky header content i.e. chapters dynamical according to the the sticky header i.e. unit which is also dynamically.

{
    "course": {
        "units": [
            {
                "unit_id": 1,
                "unit_name": "Introduction",
                "chapters": [
                    {
                        "chapter_id": 101,
                        "chapter_name": "Course Overview",
                        "duration": "10 minutes",
                        "video_path": "/videos/intro_video.mp4"
                    },
                    {
                        "chapter_id": 102,
                        "chapter_name": "Instructor Introduction",
                        "duration": "8 minutes",
                        "video_path": "/videos/instructor_intro.mp4"
                    }
                ]
            },
            {
                "unit_id": 2,
                "unit_name": "Basic Concepts",
                "chapters": [
                    {
                        "chapter_id": 201,
                        "chapter_name": "Fundamentals",
                        "duration": "15 minutes",
                        "video_path": "/videos/fundamentals.mp4"
                    },
                    {
                        "chapter_id": 202,
                        "chapter_name": "Key Terminology",
                        "duration": "12 minutes",
                        "video_path": "/videos/terminology.mp4"
                    }
                ]
            }
        ]
    }
}
3