Best approach for a simple 2d app (tournament brackets)

I would like to make a simple app for a personal use on mobile and I thought to do it here because I’m familiar with UE. I know just the basics of blueprints. It will be a tournament bracket. The app itself will be used like this:

1- I will take photos of my sons’ cars and upload it into the app
2-the app will randomize all the images and select the 8 or 16 contestants that will participate
3-I will drag and drop the winner of the first bracket and place it into the next one

This is the inspiration of the app I want to create, at 0:20 you can see the brackets scheme I need.

MONSTER TRUCK MANIA | Monster Trucks | @Hot Wheels - YouTube

I honestly don’t need a step by step, because I am eager to learn about blueprints more in depth. But I am stuck at the very beginning. What should I use to start, will the “cars” that will be randomized and displayed in the brackets are Blueprint Actors, or can I just use Widgets? The only feature as I explained, is the drag and drop. I will appreciate if you guys give me some general workflow of how something like this should be done, keywords, ideas, etc.
The point is to give my son a better experience while playing doing races with his cars, I will later add some animations, videos, effects, etc similar to that video, but I need to know the structure first. Thanks!