Hey there,
A proud/memorable project doesn't always have to be climbing mount everest or starting a company or managing 50 people. Any project or activity that makes your life and/or others life around you "better" has to be a proud/memorable project. I hope you agree with me?
So look in your personal and work life and write down all such projects. Am sure you will find many examples no matter how small. Then the real task is to showcase that work in an engaging manner for the audience (interviewer). Here I copy one of my previous answers:
Think of yourself as the lead actor/actress in your film. How would you describe your part? There is a start, middle and end. Follow STAR approach, explain context properly, provide specific quanitifable achievements, be honest and concise. Show ability to fail and learn quickly. Show that you take calculated risks and beat the bad guy out. Enjoy telling your story with nice gentle tone and pauses. Don't put a timeframe of 2/3/5mins but work with that awareness. When you speak genuinly even a long-ish answer feels very engaging. But yes, dont talk forever either.
Also have a look at this thread- https://www.preplounge.com/en/consulting-forum/how-to-start-an-answer-of-telling-a-story-about-past-projects-8188
Good luck!
Adi