Pulling resources from hard disc

Is this possible in Unreal?
I built a card game, and would love it if players could make PNGs of custom cards and use them in the game.
So I would like Unreal to be able to find a PNG in one of the game’s directories and, once selected, create a sprite from that png and spawn it in the world. Can it be done? Same thing with audio, can unreal play an audio file from the hard drive? What are my options for custom content like this?

You may want to check out the modding section of the forum for this since thats essentially what it is, just in a simplified form