nucleuscoop VS steamgriddb-manager

https://github.com/lucasassislar/nucleuscoop/releases (I found some sources leading to this but I couldn't find it in for example this Reddit or the handlers hub, very recently updated but updates are hella slow and it's not very popular)

For the people really questioning why would you need to do this, as OP pointed out in another comment, this is a great way to set up multiplayer with one machine, enabling split-screen for games that do not support it (or if you have another monitor, each one can have it's own screen!),there is even a tool that help you set up everything up nucleuscoop

link to the GitHub page

SteamGridDbManager

Sure you can do that on Steam either as adding any game as non-Steam game from menu or use tools like this to do that.

You should really use steamgriddb manager to set consistent images that's what ROMs ce done and it looks great https://www.steamgriddb.com/manager

Steam already has that feature way way before even others were a thing back then. It's https://help.steampowered.com/en/faqs/view/4B8B-9697-2338-40EC and to do this in a shortcut, you can use https://www.steamgriddb.com/manager to import your "installed" games from other launchers.

The tool https://github.com/SteamGridDB/steamgriddb-manager

Steamgriddb manager? just googled it, https://www.steamgriddb.com/manager found that it is not under development? I didn't plan to replace it, but I can imagine that there is probably some overlap.

Have you tried SteamGrid DB Manager ? It has worked to import games for Epic and other launchers before. I have Battlefront II from Epic sure also and i think I used that to import it.

steam grid db manager

for Epic and the rest: I would use https://www.steamgriddb.com/manager (or https://github.com/WombatFromHell/OriginSteamOverlayLauncher) for this sort of stuff...but it may be reliable for certain games (aka Call of Duty Warzone).

There is also this manager which is made for many launchers to be easy to import into steam. I've never used it personally and don't know if it's made for steam input in mind.