Redesign a website for portfolio?

I just completed a UX/UI design course. I am a recent mechanical engineering graduate in a European country but I am not European. I went home after I graduated and I was completely appaulled by the horrible user experience of the apps back home, banking apps, map apps, ordering apps etc. I have always enjoyed good user experience and I tend to notice when an app is designed in a way that is visually appealing.

Anyway, my goal is to gain experience from a first world country and then take it back to my country and open an agency. So, I am looking to apply to jobs in US, UK and I was just wondering if it would be ok if I would redesign one of the apps from my country. Or is it better to build something from scratch?