Happy April Fools' day! And yes, WolfenDoom becoming an Epic Store exclusive title was just an April Fools' joke.
Tim Sweeney didn't really bribe us to switch to Unreal Engine 4 and release exclusively on the Epic Store for a year.
When Chapter 3 is done, we will be releasing on this site, as well as ModDB. GNU/Linux gamers will be able to install WolfenDoom Chapter 3 from Flathub or the Ubuntu Snap Store as soon as the people maintaining those packages get around to updating them with the Chapter 3 release.