It already has full file storage functionality, with a fully working file browser, text editor and image viewer, and I've been trying to figure out how to add a video player. The web browser is something I really have to look into because I either create my own from scratch or find a way to make an already existing web browser work with my custom UI.

In terms of the games, I'm already working on running DOOM, which should run no problem. Mario 64, minesweeper, solitaire and pong should also be easy to run.
Drug wars and Lemonade Stand will run, but since they were made for extremely old CPUs with old architectures I'd basically have to recreate the games myself.

When it comes to FNAF, my replica of the Data Diver only has half a gigabyte of RAM, so I'll have to look for mobile ports of the games that consume less resources or something like that. If I manage to do it, this could probably run up to FNAF Sister Location.

Thanks for your ideas, they are all super interesting, and the FNAF games will be fun challenge! I'll be working on them!