I mean... working fine, in that the only people who buy them are pretty techy.
It's not so easy to get Win 10 working right, it requires a fair bit of effort, and the experience sucks.
I'm not so sure Steam would be super happy if Epic started distributing a new frontend and store through their marketplace. I'm quite sure they wouldn't let them.
Steam sells games which require third-party launchers to work. For example: Red Dead Redemption 2 requires the Rockstar Launcher to work (many a negative steam review regarding this), and this launcher allows you to buy other Rockstar games (The GTA franchise, LA Noire and more).
So yeah, Steam definitely allows distribution of storefronts.
They distribute games from both EA and Ubisoft that force you to use both companies launchers, that also just so happen to come with there own stores attached.
It's not so easy to get Win 10 working right, it requires a fair bit of effort, and the experience sucks.
I'm not so sure Steam would be super happy if Epic started distributing a new frontend and store through their marketplace. I'm quite sure they wouldn't let them.