Getting into YC isn't the goal here... having a successful company/product is. I would try to just build something that solves a pain point for you. If you want to prove yourself based on what you can build in 72 hours, then pick something and do it[1]. That will get you more consideration than something like this.
[1] But, I'm not a fan of "look what we built in 72 hours" types of projects, so you may want to just try to build your product.
This is really the key here. It doesn't matter where you are from. What matters is what you can do (or, in the case of proving to people that you are competent, what you have done).
Do some small thing well to show that you have a chance at doing something bigger just as well.
[1] But, I'm not a fan of "look what we built in 72 hours" types of projects, so you may want to just try to build your product.