Develop Sharepoint Site Template for Education

This is for a community college where each student creates a portfolio to represent all of their General Education classes. We want to use a Sharepoint communication site for the portfolio so that students can learn how to use Sharepoint and simultaneously build out a beautiful site that represents what they have learned in their general education courses. We just need to do a pilot to see how user friendly this option is, and we have already built the design of the site that we want to use. We have gotten stuck in trying to turn that design into a Modern Sharepoint template that has all of the pages pre-built so that students can fill in their content when they take the course. We need help developing the JSON script that will mimic this site when we import it into the "From Your Organization" template chooser. I have attached some images of the site mock up to show what I am trying to move into a template gallery.