Based on your search query, Pedagogical seems to be a suitable tool for you. It offers a range of features that can assist you in creating textbooks based on research.
The Lesson Content Extraction feature allows you to utilize your existing lesson materials to enhance the content of your textbook. This could be particularly useful if you have a wealth of research or lesson materials that you'd like to incorporate into your textbook.
Additionally, the Instructional Diagrams feature enables you to add visual aids like flow charts and mind maps to your textbook. This can help students understand complex topics and make your textbook more engaging and comprehensive.
Remember, Pedagogical is still in beta, so there might be some bugs or incomplete features. However, it offers a free plan that includes these features, making it a cost-effective solution for your needs.