What sells
Mini-ebooks: 10 to 20 pages. When the topic needs explaining.
Templates: Notion, Excel, Canva. So they don't start from scratch.
Checklists: 2 to 5 pages. Actionable, not a treatise.
Planners and swipe files: editable, or copy and paste.
Workbooks: a guide plus exercises to fill in.
Or whatever you want: an audio file, a ZIP, whatever you already solve.