Then make the Epic version include Steam instead of vice-versa. Most players will have more friends on Steam, so it’d be easier this way.
But does Steam offer a “mini-launcher” to be used on other platforms?
Maybe they do, but if so I’ve never heard of it.
(Which isn’t me defending Epic, just wondering if it is at all feasible)
Correct. But what was proposed here was a game outside of Steam using Steam’s services, which I believe isn’t a thing.
Then roll your own implementation that can support lobbies from different services, like many games already do just fine. Don’t launch a separate launcher within a launcher, it’s stupid.
so they embeded a separate launcher?? welp, it’s also not necessary, the EOS backend does not need the Epic launcher. As far as I know, the only cross platform/cross play back end is EOS. Sony have their own PC/PSN cross play in example of Helldivers 2. Capcom have their backend and the up coming Monster Hunter Wild is their first title to support cross play. (it was always separated in their past games.) Some big Chinese/Korean dev have their proprietary cross platform backend to support their mobile/console/PC games. (like Genshin)
If you do know any 3rd party cross play back end service please let me know.