We made it. Welcome to SSA. This is a crunchy topic indeed. There is a lot going on and a lot of learning to do. Let's start with a more gentle introduction.
In Grok Academy (free registration required, and your teacher may need to enrol you in the course), complete the Modelling Cyber Threats course. The aim is to get students to think about security, without thinking of coding just yet. That's to come.
After that is a shared resource that outlines in very broad terms the ideas and concepts that are to be studies.
Hacksplaining.com is a website that teaches you about vulnerabilities that can drastically affect coded solutions including PWAs. Registration is free via a google / school account.
The worksheet give students a chance to keep notes and results of work.
No surprises here, you need to know where the threats could lie so that you can code a solution for them. The following 15 slide decks were developed in class by the original Software Engineering class of 2025 to learn and better understand where threats exist so as to better understand how to code security into a solution.
Designing a secure PWA is no easy task, as can be seen from teh slide decks above. To summarise and consolidate that information, consider the following worksheet that provides some scenario based questions and concepts to ponder.
The worksheet has many components to complete and a quiz at the end to consider whether you as the end user are a "secure" web user.