Don't uninstall the game on Epic until...

[Yuveria]

.....you move your screenshot folder to another folder, You're going to lose your screenshots if you uninstall the game before taking the screenshot folder to another folder that's not located in the game folders itself, the screenshot folder is located on the same folder you installed the game
\InfinityNikkiEpicLauncher\InfinityNikkiEpic\X6Game\ScreenShot

My sister has lost all her screenshots when she uninstalled it, so I wanted to warn you all

[Grim Purrr~urut]

Yes, they are stored on your device. But you can copy this folder into new installation or to Steam.

I wrote where yo find your photos in this topic:
https://steamcommunity.com/app/3164330/discussions/0/600777026050208425/

[deathspiralli]

Thanks for the warning!

[Diblox]

There is also some things in the "Saved" folder that you can move, too. Like the Config folder for your settings.

[Dev]

That’s actually a good tip. You’d think a game that uses its own launcher would give players option to retrieve photos thru that launcher. Thanks for heads up

[DragonFlykm]

Thanks for the warning, but I don't really care about mine. I only have a few in-game that are uploaded. Everything else I delete in-game, so I don't really need the hard copies.