That’s how peertube works for streaming (not storage), with P2P

Not federated, seemingly vibecoded, MIT. Peertube exists, not sure this makes a ton of sense as an alternative but good luck otherwise.

The tool is “Steamless”. I think there was a misunderstanding, games without steam DRM don’t need an emulator. I never ran into one that lacked DRM but used the API with no fallback, thus requiring an emulator.

I am sure they exist though.

You are wrong, steam emulators are only necessary if the game uses steam DRM or relies on it for online functionality. You can try this with most indie games, or anything also sold on GOG.

You can remove the steam DRM wrapper as well quite easily if its the only one present.