PART I of your project was to identify a problem and propose a solution to address and solve the problem, differently from what might be already known/done. In other words, you said WHAT you were going to do, you promised to do something that it is supposed you know how to do it.

Now, in PART II of your project, you just have to describe HOW you are going to DO what you said you wanted to do. THE SOLUTION is the product or service that users will pay for, it is something tangible they can use. This is the essence of your engineering background, it is about the engineering design process that starts with an idea and concludes with the realization/implementation/demonstration of the idea. This is no longer about talk, this is about doing!

The demonstration of a prototype is not a compulsory element of evaluation, but it is, of course, a highly valuable element of evaluation, an element of evaluation that can make you make it or break it.

In the absence of a demonstration prototype, be it a digital App, a piece of software, some hardware, or any combination of those, you have at the very least to present, discuss and defend a credible specification of what you promise to do.

Design specification is a noble part of engineering. At a time where you are about to complete your engineering degree, I am sure you are all familiar with. If you do not know, or if you do not remember, or if you are not sure, you just need to be an entrepreneur to get to know what you need. You can search the web, you can go to the library, you can read papers, you can talk to colleagues, you can talk to professors, you can and should do whatever you need to get to know what you need. What you can not do, should not do, is sitting quietly in your space of ignorance and wait for someone to tell you what to do. You know this will not happen.
For those of you who might not be able to have the initiative to navigate your space of interest, I leave here just a few keywords that could help ignite your willingness to learn.

Try: "Design Specifications", "Engineering Design Process", you will be astonished by the vast amount of information at your disposal.

Try: "Prototyping an Idea", "Hardware Prototype Development Process", again, no lack of information, just need the willingness to learn what you need.

Try: "App design specifications", "App Demonstration", there is no lack of information and knowledge available at your disposal to help you do what you have promised to do!