Logbooks are very popular on Amazon. They can be anything from blood pressure logs, sign-in books, vehicle registration logbooks, gardening logs, expense trackers…just about anything!
You would create a logbook in the same way as you would a planner, by using either Canva or whatever program you prefer.
Searching Amazon for ideas can help trigger your own. If you find a niche with high demand and low competition, you could be on to a winner!