If you were a novice painter/cook/carpenter/sculptor/singer/accountant/mechanic what would you include in a portfolio? Now, the portfolio exists to demonstrate a skill you posess.
You'd look for established people and their works from your domain and copy them to study their methods, their style. Figure out and differentiate the core from the frills. Tweak, mix, combine, jam and fuse what you've learnt.
Then you'd merge your favorite styles together to create your own, novel work. Repeat enough times and you have a solid portfolio.
Unfortunately, the programming world is crippled with 'get rich quick' apps/websites/products.
Most newbie programmers believe that unless they have a novel idea, they cannot and should not build an app or a website. That attitude sucks the life and joy out of learning anything including programming.
I strongly urge you to copy, steal and be inspired by as many apps and websites as you can before going for novelty.
What you will learn in the process far outweighs any commercial success that you can hope for.
Good luck.